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APPLIED  ENTOMOLOGY 

AN  INTRODUCTORY  TEXT-BOOK 

OF 
INSECTS  IN  THEIR  RELATIONS  TO  MAN 


BY 

H.  T.  FERNALD,  PH.D. 

PROFESSOR   OF   ENTOMOLOGY,   MASSACHUSETTS  AGRICULTURAL  COLLEGE,   AND 

ENTOMOLOGIST   OF   THE   MASSACHUSETTS   AGRICULTURAL 

EXPERIMENT    STATION 


FIRST   EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 

NEW  YORK:    370  SEVENTH  AVENUE 

LONDON:    6  &  8  BOUVERIE  ST.,  E.  C.  4 

1921 


^  '  / 

C>  C\         '  C       ?  !  o  r  a>  r 


FORESTRY  LIBRARY 


COPYRIGHT,  1921,  BY  THE 
McGnAw-HiLL  BOOK  COMPANY,  INC. 


THE    MAfXii;    PRESS    YORK 


TO   THE    MEMORY    OF 


PROFESSOR  CHARLES  H.  FERNALD: 

the  first  teacher  of  Economic  Entomology 
to  college  students,  in  this  country. 


.  .      .  •;'  PREFACE  . 

If  one  can  judge  from  the  answers  to  about  fifty  letters  of  inquiry 
sent  to  teachers  of  Entomology  in  colleges  in  the  United  States,  the 
teaching  of  Entomology  in  this  country  at  the  present  time  is  in  a  rather 
chaotic  condition.  Very  few  of  the  answers  received  show  much  in 
harmony  in  subject  matter,  methods  of  presentation,  or  even  the  line  of 
training  the  students  should  receive  by  a  course  in  the  subject. 

The  author  believes  that  in  agricultural  colleges  at  least,  two  distinct 
groups  of  students  need  a  knowledge  in  Entomology,  and  rather  early  in 
their  course.  One  of  these  groups  is  composed  of  students  who  will 
never  specialize  in  the  subject  but  need  it  as  part  of  an  agricultural 
education,  and  particularly  as  a  tool  which  they  can  use  wherever  insects 
are  related  to  their  special  lines  of  work.  They  are  not  particularly 
interested  in  such  details  as  the  number  of  antennal  segments  in  insects, 
the  number  of  branches  of  the  radial  vein,  or  how  important  a  pest  on 
pigweed  the  insect  is:  they  do  not  expect  to  identify  insects  beyond  the 
order  or  family  at  most,  relying  on  specialists  available  at  the  State 
Experiment  Stations  for  such  information.  But  they  do  desire  a  general 
knowledge  of  the  broad  outlines  of  the  subject,  and  a  rather  complete 
knowledge  of,  and  if  possible,  the  ability  to  recognize  particularly  import- 
ant insect  pests  they  are  liable  to  meet  in  the  course  of  their  work. 

The  other  group  consists  of  those  who  expect  to  specialize  in  the 
subject,  becoming  professional  entomologists.  Their  needs  will,  of 
course,  be  different  from  those  of  the  other  group,  but  an  introductory 
survey  such  as  will  meet  the  requirements  of  the  rest  will  give  the  members 
of  this  group  an  excellent  foundation  for  further  and  more  detailed  work. 

The  present  book  is  therefore  offered  as  a  classroom  text  for  an 
introductory  course  in  the  subject,  which  shall  give  a  general  idea  of 
insects,  their  structure,  life  histories  and  habits,  with  methods  for  the 
control  of  insect  pests  in  general,  followed  by  a  more  thorough  study  of 
the  more  important  ones  found  in  this  country.  For  use,  the  writer 
believes  that  in  few  places  will  all  of  the  text  be  assigned.  Instead,  the 
pests  of  the  country  as  a  whole  (treated  in  large  type)  and  those  of  the 
particular  region  concerned  (selected  from  among  those  printed  in  smaller 
type)  would  naturally  be  the  parts  used  in  any  one  place,  though  the 
book  as  a  whole  should  be  fairly  well  applicable  to  all  sections  of  the 
country. 

The  author  is  of  the  opinion  that  to  avoid  too  much  monotony,  it 
may  prove  wise  to  assign  Chapters  VI  to  IX  inclusive,  among  those 


viii  PREFACE 

immediately  following.     The  treatment  of  the  subject  matter  is  such  as 
to  permit  this. 

Many  of  the  illustrations  included  are  familiar.  Where  satisfactory 
illustrations  are  already  available,  it  is  questionable  whether  new  ones 
are  any  gain,  particularly  when  all  are  new  to  the  student.  In  this 
connection  the  author  desires  to  express  his  grateful  appreciation  of  the 
kindness  of  Dr.  W.  E.  Britton  and  the  Connecticut  Experiment  Station, 
and  of  Prof.  J.  S.  Houser  and  the  Ohio  Experiment  Station,  for  the  pro- 
vision of  cuts  from  the  publications  of  those  Stations.  He  is  much 
indebted  to  Prof.  E.  D.  Sanderson  for  the  use  of  cuts  taken  from  "  Insect 
Pests  of  Farm,  Garden  and  Orchard"  and  from  Sanderson  and  Jackson's 
"  Elementary  Entomology,"  and  to  the  publishers  of  these  books,  John 
Wiley  and  Sons,  Inc.,  and  Ginn  and  Company  respectively,  as  well  as  to 
Dr.  E.  P.  Felt  who  has  kindly  allowed  the  use  of  reproductions  of  illus- 
trations taken  from  his  publications.  Dr.  J.  W.  Folsom's  kindness  and 
that  of  his  publishers,  P.  Blakiston's  Sons  and  Company  in  permitting 
the  use  of  illustrations  from  Dr.  Folsom's  book  "  Entomology  with 
Reference  to  its  Biological  and  Economic  Aspects,"  is  also  much  appre- 
ciated. Ginn  and  Company  have  kindly  consented  to  the  use  of  several 
illustrations  from  Linville  and  Kelly's  "Textbook  in  General  Zoology," 
and  the  side  view  of  the  parts  of  a  grasshopper  has  been  obtained  by 
permission  of  those  in  charge  of  the  Natural  History  Survey  of  Connecti- 
cut. The  largest  number  of  illustrations  secured,  however,  has  been 
obtained  through  the  kind  permission  of  Dr.  L.  0.  Howard  of  the  U.  S. 
Bureau  of  Entomology  to  use  many  which  are  the  property  of  the  Bureau. 
Photographs  from  various  Experiment  Station  Reports  and  Bulletins 
have  also  been  freely  drawn  upon.  The  source  from  which  each  illus- 
tration has  been  obtained  is  indicated  in  every  case.  To  all  the  persons 
and  companies  above  named,  I  desire  to  express  my  thanks. 

Any  book  such  as  this  is  necessarily  a  compilation.  Probably  there 
are  very  few  if  any  entomologists  in  this  country  who  have  worked  per- 
sonally on  all  the  insects  treated  here.  The  only  originality  for  it 
which  can  be  claimed  therefore,  is  in  the  selection  of  the  various  topics 
and  their  method  of  presentation.  Errors  have  undoubtedly  crept  in, 
and  the  author  will  appreciate  having  his  attention  called  to  any  which 
may  be  found. 

The  author  desires  to  express  his  appreciation  of  the  aid  in  the  pre- 
paration of  this  book  given  him  by  his  associates,  Dr.  G.  C.  Crampton, 
Dr.  W.  S.  Regan,  and  Mr.  A.  I.  Bourne,  who  have  gone  over  various 
parts  of  it  and  have  criticized  and  advised  on  those  which  they  have 
examined.  Much  of  any  value  it  may  have  is  due  to  them,  but  for  any 
errors  and  incorrect  statements  which  may  be  found,  the  author  assumes 
full  responsibility. 

AMHEBST,  March  1,  1921.  H.  T.  FERNALD. 


CONTENTS 

PAGE 
PREFACE .~    .    .     vii 

CHAPTER  I 

INSECTS  AND  OTHER  ANIMALS. »   .    .    .    ,    ,    .     ,1 

The  larger  groups  of  animals — Their  distinctive  characters — The  Arthropoda 
— Its  characters — Animals  included — Subdivisions  of  the  group — Their 
distinctive  characters — Tabular  statement  of  the  distinctive  characters. 

CHAPTER  II 

THE  INSECT:  ITS  EXTERNAL  STRUCTURE . .       0 

The  characters  of  insects — Number  of  segments  in  the  embryo — In  the 
adult — The  hypodermis — Sutures — Plates — Form  of  head — Structures  on 
the  body — The  antennae — Eyes — Mouthparts — Chewing  mouthparts — 
The  thorax — Its  appendages — Legs — Wings — The  abdomen — Abdominal 
feet — Ovipositors-Other  appendages . 

CHAPTER  III 

THE  INSECT:  ITS  INTERNAL  STRUCTURE 15 

Digestive  organs — Breathing  organs — Circulatory  organs — The  blood — 
Excretory  organs — Nervous  system — Sense  organs — Reproductive  organs. 

CHAPTER  IV 

THE  DEVELOPMENT  OF  INSECTS 25 

Egg-laying  and  viviparous  insects — Description  of  insect  eggs — Hatching — 
Development  of  the  insect — The  Ametabolous  development — Hemime- 
tabolous  development — Holometabolous  development — Pupation  and 
cocoon  making — Transformation  of  the  pupa — Emergence — Common 
names  of  Holometabolous  larvse. 

CHAPTER  V 

LOSSES  CAUSED  BY  INSECTS:  NATURE'S  CONTROL  METHODS 32 

Amount  of  the  loss  not  generally  realized — Its  average  amount — To  crops — 
To  animals  and  their  products — To  forests  and  their  products — To  stored 
materials — By  disease — Total  loss — Losses  increasing — Causes — Intro- 
duction of  foreign  insect  pests — Reduction  in  abundance  of  insectivorous 
birds — A  theoretic  state  of  equilibrium  upset  by  civilization — Nature's 
methods  too  slow — Artificial  methods  necessary. 

CHAPTER  VI 

ARTIFICIAL  METHODS  OF  CONTROL 38 

Two  groups  of  methods — Farm  practice — Healthy  crops — Crop  rotation- 
Plowing — Time  of  planting — Resistant  varieties  of  plants — Trap  crops- 
Special  methods — Hand    picking — Repellents — Trap  lanterns — Burning — 
Heat — Miscellaneous  methods. 


x  CONTENTS 

CHAPTER  VII 

PAGE 

INSECTICIDES  IN  GENERAL:  STOMACH  POISONS 43 

Materials  classified — Conveyance — Dusts — Sprays — Arsenic — Disadvan- 
tages— Paris  green — Disadvantages — Standard  formula — Variations — 
Arsenate  of  lead — Standard  formula — Arsenate  of  lime — Standard  formula — 
Poison  baits — Hellebore — Commercial  Sodium  Fluorid. 

CHAPTER  VIII 

CONTACT  INSECTICIDES 49 

Purposes  of  contact  insecticides — Kerosene  emulsion — Miscible*  oils — 
Whale-oil  soap — Common  soap — Nicotine — Nicotine  sulfate — Lime  sulfur 
wash- — Dry  sulfur  compounds — Sulfur — Pyrethrum,  insect  powder,  or 
buhach. 

CHAPTER  IX 

INSECTICIDES  AND  FUNGICIDES:  FUMIGATION 54 

Combinations  of  spray  materials — Of  insecticides — Of  insecticides  and 
fungicides — Injurious  combinations — fumigation — Nature  of  its  action — 
Limits  of  availability — Carbon  disulfid — Nicotine — Sulfur — Hydrocyanic- 
acid  gas. 

CHAPTER  X 

THE  RELATIONSHIPS  OP  INSECTS 59 

Classification — The  development  of  animals  in  the  past — Artificial  and 
natural  classifications — The  original  insects— The  development  of  diversity 
— Resultant  groups — Relations  of  species,  genera,  families  etc. — A  sample 
tree-like  classification — Table  of  classification. 

CHAPTER  XI 

THE  APTERYGOTA 62 

General  structure — Distinctive  characters — General  description — Divisions 
of  the  group — Order  Thysanura — Distinctive  characters — The  Silver  Fish — 
Order  Collembola — General  features — Distinctive  characters — General 
account. 

CHAPTER  XII 

THE  PTERYGOTA.     THE  EPHEMERIDA 65 

General  considerations  on  the  Pterygota — The  Ephemerida — General 
description  and  structure — Distinctive  characters — Life  and  habits — 
Importance. 

CHAPTER  XIII 

THE  ODONATA 68 

General  description  and  structure — Distinctive  characters — Groups  of 
dragon-flies — Habits — Their  life  and  food — Importance — Abundance. 

CHAPTER  XIV 

THE  PLECOPTERA 72 

General  description  of  the  group — Distinctive  characters — Life  and  habits — 
Abundance — Economic  importance. 


CONTENTS  xi 

CHAPTER  XV 

PAGE 

THE  EMBIIDINA .......    *    .    .     74 

General  description — Economic  importance. 

CHAPTER  XVI 

THE  ORTHOPTERA     .    .    .    ...'..    .    ,    .    .    . ...    .     75 

General  description — Structure — Division  into  two  sections — The  Cursoria 
— Distinctive  characters — Families  considered — The  Blattidse — Descrip- 
tion of  Roaches — The  German  Roach — The  American  Roach — The  Aus- 
tralian Roach — The  Oriental  Roach  or  "black  beetle" — Control  of  Roaches 
— The  -Mantidae — General  considerations — Common  Mantids — The  Phas- 
midse — General  description  of  appearance,  life  history  and  habits — Eco- 
nomic importance — Control — The  Saltatoria — General  features — The  Acri- 
didse — Description  of  grasshoppers — Abundance — Economic  importance — 
Control — Kinds  of  grasshoppers — Sounds  produced — Organs  of  hearing — 
The  Tettigoniidse — General  description  of  the  family,  habits,  life  history, 
etc. — Economic  importance — The  Gryllidse — General  statements — Sounds — 
Ears — Economic  importance — Kinds  of  crickets — Tree  crickets — Control. 

CHAPTER  XVII 

THE  ISOPTERA 91 

The  colony — Its  composition — Castes — Structures — Distinctive  characters 
— Food — Swarming — Common  species — Life  and  habits — Injuries — Control 
— Zoraptera. 

CHAPTER  XVIII 

THE  DERMAPTERA V ,    .    . 95 

General  description — Distinctive  characters — Importance — Habits — 
Different  species — The  European  earwig — Injuries — Control. 

CHAPTER  XIX 

THE  COLEOPTERA 98 

Structure — Distinctive  characters — Life  histories  and  habits — Division  into 
Coleoptera  vera  and  Rhynchophora — Coleoptera  vera — Lampyridse — 
Carabidae — •  Cicindellidae — Dytiscidse —  Gyrinidae — Hydrophilidse — Staphy- 
linidae — Silphidae — Dermestidse — Larder  beetle — Buffalo  Carpet  beetle — 
—Black  Carpet  beetle — Control — Buprestidse — Flat-headed  Apple-tree 
Borer — Elateridae — Wireworms — control — Scarabseidae — June  bugs — Rose 
chafer — -Japanese  Beetle — Chrysomelidae — Colorado  Potato  Beetle—- 
Change of  food  a  possible  pest  producer — Striped  Cucumber  Beetle — Corn- 
root  Worms — Flea  Beetles — Asparagus  Beetles — Grape  Root  Worm — Elm 
Leaf  Beetle — Tortoise  Beetles— Bruchidse — Pea  Weevil — Bean  Weevil- 
Broad  Bean  Weevil — Control  of  Weevils — Cerambycidae — Round-headed 
Apple-tree  Borer — Coccinellidee — Tenebrionidae — Yellow  Meal-worm — 
Meloidae — Rhynchophora — Plum  Curculio — Plum  Gouger — Cotton  Boll 
Weevil — White  Pine  Weevil — Alfalfa  Weevil — Potato-stalk  Weevil — Sweet- 
potato  Weevil — Ipidae — Fruit-tree  Bark  Beetle. 


xii  CONTENTS 

CHAPTER  XX 

PAGE 

THE  STREPSIPTERA 150 

General  description — Distinctive  characters — Habits — Life  history — Abun- 
dance— Importance. 

CHAPTER  XXI 

THE  THYSANOPTERA 153 

General  features — Structure — Distinctive  characters — Habits — Subdivisions 
— Wheat  Thrips — Onion  Thrips — Pear  Thrips — Citrus  Thrips. 

CHAPTER  XXII 

THE  CORRODENTIA 159 

General  description — Structure — Distinctive  characters — Book  lice — 
Psocids — Importance  of  the  group. 

CHAPTER  XXIII 

THE  MALLOPHAGA 161 

General  features — Distinctive  characters — Habits — Poultry  lice — Control. 

CHAPTER  XXIV 

THE  ANOPLURA 164 

Description — Distinctive  characters — Distribution — Life  history — Body 
louse — Relation  of  lice  to  disease — Crab  louse — Lice  on  domestic  animals — 
Control. 

CHAPTER  XXV 

THE  HEMIPTERA 168 

General  characters — Structure  of  mouthparts — Distinctive  characters — 
Distribution — Habits — Pentatomidse — Harlequin  Bug — Cydnidse — Coreidaj 
— Squash  Bug — Pyrrhocoridre — Cotton  Stainer — Lygseida3 — Chinch  Bug 
—The  diseases  of  Insects — Tingitidte — Miridse — Meadow  Plant  Bug — Tarn- 
ished Plant  Bug — Phymatidse — Reduviidse — Cimicida3 — Bedbug — Gerridae 
— Notonectidae — Corixidae — Nepidae — Belostomidae. 

CHAPTER  XXVI 

THE  HOMOPTERA 186 

General  statements — Distinctive  characters — Variations  in  habits  etc. — 
Honey  dew — Classification  of  the  order — Cicadidse — Periodical  Cicada  or 
17-year  Locust — Leaf  Hoppers  and  Tree  Hoppers — Apple  Leaf  hoppers — 
Rose  Leaf  hopper — Chermidse — Pear  Psylla — Aphididaa  in  general — Apple 
Aphids — Grape  Phylloxeras-Corn  Root  Aphis — Aleyrodidse — Coccidse 
in  general — Armored  Scales — Oyster-shell  Scale — Scurfy  Scale — San  Jose 
Scale— Rose  Scale— Pine  Leaf  Scale— Purple  Scale— Red  Scale— Soft 
Scales — Black  Scale — Terrapin  Scale — Cottony  Maple  Scale — Hemispherical 
Scale — Mealy  Bugs — Citrus  Mealy  Bug — Long-tailed  Mealy  Bug — Cottony 
Cushion  Scale — Introduction  of  enemies  of  introduced  pests. 


CONTENTS  xiii 

CHAPTER  XXVII 

PAGE 

THE  NEUROPTERA 221 

General  features — Distinctive  characters — Economic  value — Sialidse — 
Corydalis — Chrysopidae  or  Aphis  lions — Raphidiidae — Mantispidae — Myrme- 
leonidic  or  Ant  lions. 

CHAPTER  XXVIII 

THE  TRICHOPTERA .    .    ,    .    . .    .    .    .   226 

General  description — Distinctive  characters — Life  and  habits — Larval  cases 
— Importance. 

CHAPTER  XXIX 

THE  LEPIDOPTERA .    .    .    ,   .    .    .    .  ; ;......   230 

General  features — Structure — Mouthparts — Distinctive  characters — Diver- 
sity in  the  order — Life  history  and  development  in  general — Cossidae— 
Leopard  Moth — Tineidse — Clothes  moths  and  their  control — Codling  Moth 
— vEgeridae — Peach  Borers — Squash-vine  Borer — Gelechiidse — Angoumois 
Grain  Moth — Pterophoridae — Pyralidae — Bee  Moth — European  Corn  Borer 
— Limacodidse  —  Psychidae — Geometridae  —  Canker  worms — Bombycidse — 
Lasiocampidae — Apple-tree  Tent-caterpillar — Forest  Tent-caterpillar — Ly- 
mantriidae — White-marked  Tussock  Moth — Antique  or  Rusty  Tussock 
Moth — Gypsy  Moth — Brown-tail  Moth — Notodontidae — Dioptidae — Cali- 
fornia Oak  Worm — Noctuidae  in  general — Cotton  Worm — Corn-ear  Worm 
— Army  Worm — Fall  Army  Worm — Cutworms — Arctiidae — Fall  Web-worm 
— Ceratocampidae — Saturniidae — Sphingidae — Tobacco  and  Tomato  Worms 
—  The  Butterflies  —  Hesperiidae  —  Lycaenidae  — Danaidae  — Ny  mphalidae — 
Satyridae — Pieridae — Imported  Cabbage  Butterfly — Sulfur  butterflies — The 
spreading  over  the  country  of  introduced  insects — Papilionidae — Black 
Swallow-tail  butterfly. 

CHAPTER  XXX 

THE  MECOPTERA 300 

General  features — Distinctive  characters — Habits — Food — Importance. 

CHAPTER  XXXI 

THE  DIPTERA 301 

General  description — Structure — Mouthparts  of  adult — Larvae — Pupae — 
Distinctive  characters — Size  and  importance  of  the  group — Tipulidae — 
Culicidse — House  Mosquito — Malarial  Mosquitoes — Relation  to  malaria — 
Yellow  Fever  Mosquito — Control  of  mosquitoes — Itonididae — Clover- 
flower  Midge — Hessian  Fly — Wheat  Midge — Tabanidae — Simulidae — 
Asilidae — Syrphidae — (Estridae — Ox  Warbles — Trypetidae — Apple  Maggot — 
Muscidae — House  Fly — Its  relation  to  disease — Screw  Worm  Fly — Sarco- 
phagidae — Tachinidae — Tsetse  Flies — Anthomyiidae — Cabbage  Maggot — 
Onion  Maggot — Pupipara — Sheep  Tick. 

CHAPTER  XXXII 

THE  SIPHONAPTERA  . 333 

General  description — Structure — Distinctive  characters — Food — Life  his- 
tory and  habits — Relation  to  disease— Control — "Sticktight  flea" — Chigoe. 


xiv  CONTENTS 

CHAPTER  XXXIII 

PAGE 

THE  HYMENOPTERA 338 

General  description  and  structure — Terebrantia  and  Aculeata — Develop- 
ment —  Distinctive  characters  —  Importance  —  Tenthredinoidea  —  Currant 
Worm — Pear  Slug — Wheat  Stem  Borers — Horn-tails — Ichneumonoidea — 
Their  importance — Methods  of  work — Long-tailed  Thalessa— Cynipoidea — 
Gall  production — Alternation  of  generations — Inquilines — Parasites — Impor- 
tance of  galls — Chalcidoidea — Habits — Wheat  Straw  Worm — Wheat  Joint 
worm — Clover-seed  Chalcis — Fig  Blastophaga — Pteromalus  puparum — 
Serphoidea — Long-tailed  Pelecinus — Variation  in  habits  of  parasitic  Hymen- 
optera — Chrysidoidea — Sphecoidea— Vespoidea — Progressive  development 
as  illustrated  by  Wasps — Apoidea — Solitary  bees — Leaf-cutter  bees — 
Carpenter  bees — Bumble  bees — Honey  bee — Life  of  a  Honey  bee  colony — 
Swarming — Value  of  bee  products — Formicoidea — Composition  of  ant 
colonies — Location  of  colonies — Swarming — Establishment  of  new  colonies — 
Ants  and  plant  lice,  etc. — Unusual  habits — Argentine  Ant — House  Ants — 
Ants  in  lawns. 


APPLIED  ENTOMOLOGY 

CHAPTER  I 
INSECTS  AND  OTHER  ANIMALS 

Among  the  larger  groups  of  animals  now  recognized  by  science,  the 
one  known  as  the  Chorda  fca  is  naturally  the  most  familiar,  including  the 
mammals,  birds,  reptiles,  fishes,  besides  numerous  forms  less  well  known. 
Another  group,  also  familiar,  and  called  the  Mollusca,  includes  the  snails, 
clam  etc.,  while  a  third,  the  Annulata,  contains  most  of  the  more 
commonly  seen  worms.  The  starfish  and  sea  urchins,  often  seen  at  the 
seashore,  belong  with  other  similar  animals,  to  a  fourth  group  called  the 
Echinodermata,  and  a  multitude  of  tiny  beings  almost  all  too  small  to  be 
seen  without  the  aid  of  a  microscope,  are  included  in  the  group  Protozoa. 
A  sixth  large  group  is  composed  mainly  of  soft,  jelly-like  animals,  the 
more  common  larger  members  being  called  jelly-fish,  and  to  this  the 
name  Ccelenterata  is  applied,  and  several  other  groups  of  less  familiar 
forms  are  also  known. 

The  largest  group  of  all,  however,  is  the  Arthropoda,  its  members 
found  in  the  seas,  in  fresh  water,  on  land,  or  even  flying  freely;  a  group 
with  remarkable  differences  of  structure,  and  so  abundant  that  all  the 
other  animals  taken  together  are  less  than  one-sixth  as  many  as  the 
Arthropods.  Well-known  members  of  this  group  are  the  lobsters,  cray- 
fish and  crabs;  scorpions,  spiders,  mites,  ticks  and  "  daddy  long  legs;" 
the  centipedes  and  millipedes;  and  last  and  most  abundant  of  all,  the 
Insects. 

No  one  feature  will  serve  to  separate  the  Arthropods  from  all  other 
animals,  but  the  possession  by  an  animal  of  several  of  those  here  described 
will  enable  the  observer  to  determine  in  each  case  whether  he  is  examin- 
ing one  of  this  group.  In  Arthropods  the  body  is  composed  of  a  series  of 
more  or  less  similar  pieces  or  segments,  placed  one  behind  another,  the 
line  of  attachment  of  these  to  each  other  being  usually  somewhat  evident 
on  parts  of  the  body  at  least.  This  character  is  also  shown,  and  indeed 
more  clearly,  in  some  members  of  the  Annulata,  such  as  the  common 
earthworm.  Another  character  of  the  Arthropods  is  the  presence  of 
jointed  legs  (or  appendages  of  some  kind),  as  is  indicated  by  the  name 
of  the  group,  and  these  are  not  possessed  by  Annulates.  The  surface  of 
the  body  is  covered  by  a  secretion  which  hardens  on  exposure  to  the  air, 

1 


APPLIED  ENTOMOLOGY 


forming  an  outside  shell  or  external  skeleton  (exo-skeleton),  there  being 
practically  no  internal  supporting  structures  except  as  ingrowths  from 
the  outside.  In  the  possession  of  this  external  skeleton  these  animals 

have  a  seeming  resemblance  to  the 
shells  (Mollusca),  but  the  materials 
of  which  it  is  composed  are  quite 
different,  being  largely  calcium  car- 
bonate in  the  Mollusca,  and  chitin 
which  somewhat  resembles  horn  in 
its  nature,  sometimes  with  calcareous 
salts  deposited  in  it,  in  the  Arthro- 
poda.  In  its  simplest  members  the 
Arthropod  body  is  also  practically 
bilaterally  symmetrical,  though  this 
condition  is  concealed  somewhat  by 
secondary  changes  in  many  of  the 
group.  The  possession  of  a  bilaterally 
symmetrical  body  consisting  of  a 
series  of  segments;  an  exoskeleton  of 
chitin,  and  the  presence  of  jointed 
legs,  are  then,  distinctive  features  of 
the  Arthropods. 

To  separate  the  various  groups  of  Arthropods,  other  characters  must 
be  used.  Aside  from  several  small  sections  not  often  seen,  there  are  five 
large  and  important  divisions  which  call  for  recognition.  These  are  the 
Crustacea,  including  the  lobster,  crab,  beach  flea,  sow  bug  and  many 


FIG.    1. — Crayfish     (Crustacea);    about 
one-half  natural  size.     (Original.) 


FIG.  2.  -J—  "Sow-bug;  a  crustacean 
living  on  land;  about  natural  size. 
(Original.) 


FIG.  3.— Millipede  (Diplopoda);  natural  size. 
(From  Folsom.) 


others;  the  Diplopoda  or  Millipedes;  the  Chilopoda  or  Centipedes;  the 
Hexapoda  or  Insects;  and  the  Arachnida,  including  the  scorpions,  pseudo^ 
scorpions,  spiders,  mites,  ticks,  etc. 


INSECTS  AND  OTHER  ANIMALS  3 

The  Crustacea  (Fig.  1)  are  mainly  water-inhabiting  animals  which 
breathe  either  by  gills,  or,  in  the  smaller  forms,  through  the  surface  of 
the  body.  In  those  cases  where  its  members  live  on  land  (Fig.  2)  the  gills 
are  still  present,  though  in  a  somewhat  modified  condition.  They  have 
numerous  pairs  of  legs  and  generally  two  pairs  of  antennae  (jointed 
"feelers")-  Often  some  of  the  body  segments  are  fused  with  the  head 
to  form  a  cephalothorax. 

The  Diplopoda  (Fig.  3)  are  land  animals  breathing  by  air  tubes  open- 
ing on  the  sides  of  the  body  and  permitting  the  air  to  pass  in  to  all  the 
internal  parts  of  the  animal.  The  head  bears  a  pair  of  antennas  and  is 
followed  by  a  series  of  segments  all  practically  alike  and  each,  except 


FIG.  4. — Centipede  (Chilopoda);  about  three-quarters  natural  size.     (Original.) 


the  first  three,  with  two  pairs  of  legs.  The  reproductive  organs  open 
far  forward  on  the  body.  In  most  of  the  more  common  members  of 
this  group  the  body  is  quite  cylindrical  and  when  disturbed  the  animal 
usually  curls  up  in  a  sort  of  close  spiral.  Small  Diplopods  about  the 
diameter  of  the  lead  of  a  pencil  and  gray  in  color  are  often  found  boring 
into  potatoes  and  roots  in  the  ground  in  the  fall,  and  are  sometimes 
wrongly  called  wire  worms.  The  common  name  "  millipede"  refers  to 
the  large  number  of  legs  possessed  by  these  animals. 

The  Chilopoda  are  also  land  animals  (Fig.  4).  Like  the  Diplopods 
they  have  antennae;  breathe  by  air  tubes,  and  the  body  segments  are 
practically  all  alike.  The  general  form,  however,  is  rather  flattened; 
each  segment  bears  only  one  pair  of  legs,  and  the  reproductive  organs 
open  at  the  hinder  end  of  the  body.  The  front  leg  on  each  side  is  modi- 


APPLIED  ENTOMOLOGY 


fied  to  serve  as  a  poison  claw.    The  numerous  legs  present  in  these 
animals  has  resulted  in  their  receiving  the  common  name  "  centipede." 


FIG.  5. — Hairy  Spider   (Arachnida);  about       FIG.    6. — Large  bodied  Spider  (Arachnida), 
natural  size.     (Original.}  about  natural  size.      (Original.) 


FIG.  7. — Adult  female  castor-bean  Tick  FIG.    8. — Adult   female    European    dog 

(Arachnida);    natural    size.      (From    U.  S.       Tick  (Arachnida);  natural  size.    (From  U.S. 
D.  A.  Farm.  Bull.  1057.)  D.  A.  Farm.  Bull.  1057.) 


FIG.  9. — Grasshopper   (Insecta);  with  wings  spread.     (From  Folsom.) 

The  Arachnida  (Figs.  5,  6,  7  and  8)  generally  have  the  segments  of  the 
body  grouped  into  two  sections  called  the  cephalothorax  and  abdomen. 


INSECTS  AND  OTHER  ANIMALS 


No  antennae  are  present  and  the  eight  legs  are  all  attached  to  the  first- 
named  section.  They  breathe  either  by  air  tubes  somewhat  similar  to 
those  of  the  other  groups;  by  sacs  containing  many  thin  plates  resembling 
leaves  of  a  book,  whence  these  structures  take  the  name  of  book-lungs; 
or,  in  the  smallest  forms,  directly  through  the  body  surface.  In  the 
mites  there  is  no  evident  division  of  the  body  into  sections.  Though 
most  of  the  group  are  land  forms,  a  few  are  aquatic. 

In  the  Hexapoda  or  Insects  (Fig.  9)  the  segments  of  the  body  are 
grouped  in  three  distinct  sections;  the  head,  thorax  and  abdomen.  A 
pair  of  antennae  is  (with  rare  exceptions)  present  on  the  head;  the  six 
legs  are  attached  to  the  thorax  as  are  the  four  wings  usually  present; 
the  animals  breathe  by  air  tubes;  and  while  living  under  a  great  diversity 
of  conditions,  the  group  as  a  whole  is  emphatically  a  terrestrial  one, 
though  in  many  cases  their  early  life  is  spent  in  water. 

DISTINCTIVE  CHARACTERS  OF  THE  MAIN  ARTHROPOD  GROUPS 


Where 
found 

Body  divisions 

Antennae 

Legs 

Breathe  by 

Reproduc- 
tive organs 
open 

Crustacea  .... 

Mainly  in 
water 

Head  and  body: 
often  a  cepna- 
lothorax 

Two  pairs 
generally 

Numerous:  may 
be    built    for 
swimming 

Gills  or  through 
body  surface 
(rarely  by  air 
tubes; 

Well  forward 

Diplopoda.  .  . 

On  land 

Head  and  body 

One  pair 

Many:  two 
pairs  on  most 
body  seg- 
ments 

Air  tubes 

Near  head 

Chilopoda.  .  .  . 

On  land 

Head  and  body 

One  pair 

Numerous:  one 
pair  on  each 
body  segment 

Air  tubes 

Next  to  last 
body   seg- 
ment 

Arachnida.  .  . 

Mainly  on 
land 

Cephalothorax 
and  abdomen 
(no    divisions 
in  a  few  cases) 

None 

Eight:  joined 
to  cephalo- 
thorax 

Air  tubes,  book- 
lungs  or  body 
surface 

Front  part  of 
abdomen 
(a    few    ex- 
ceptions) 

Hexapoda.  .  .  . 

Mainly  on 
land 

Head,    thorax, 
abdomen 

One  pair 

Six:  joined  to 
thorax 

Air  tubes 

Near  hind  end 
of  abdomen 

CHAPTER  II 
THE  INSECT  :  ITS  EXTERNAL  STRUCTURE 

Bringing  together  the  facts  about  insects  already  stated,  we  find  that 
an  adult  insect  is  a  bilaterally  symmetrical  animal  consisting  of  a  series 
of  segments  one  behind  another,  and  that  these  segments  are  grouped 
into  three  regions,  the  head  in  front,  followed  in  order  by  the  thorax  and 
the  abdomen  (Fig.  10).  Covering  the  animal  is  a  skeleton,  shell-like  in 
that  it  encloses  the  body,  but  horny  in  its  nature.  Attached  to  the  seg- 


antennae 


"tarsus 


FIG.  10. — Side  view   of  Grasshopper  with  parts  named.      (From   W olden,   Conn.  Geol.  & 

Nat.  Hist.  Surv.,  Bull.  16.) 

ments  are  three  pairs  of  jointed  legs,  a  pair  of  antennae,  mouth  parts  and 
usually  two  pairs  of  wings.  It  breathes  through  air  tubes,  and  the 
reproductive  organs  open  near  the  hinder  end  of  the  body. 

The  adult  insect  does  not  show  all  the  segments  of  which  its  body  is 
composed.  In  the  embryo  evidences  of  21  have  been  found,1  but  as  the 
animal  progresses  toward  maturity  some  of  these  fuse  with  others.  The 
head  of  the  adult,  though  apparently  consisting  of  only  one  segment,  is 
now  believed  to  be  the  product  of  the  fusion  of  six:  the  three  found  in 
the  adult  thorax  seem  to  have  always  been  that  number;  and  the  abdo- 
men, composed  of  12  segments  in  the  embryo  appears  to  have  been  re- 
duced in  the  adult  to  a  number  varying  from  three  to  11,  partly  by  a 

1  Some  investigators  believe  that  22  segments  are  present,  the  head  consisting  of 
seven,  but  this  view  is  not  universally  accepted. 

6 


THE  INSECT:  ITS  EXTERNAL  STRUCTURE 


ce 


arrt. 


process  of  fusion,  partly  by  a  sort  of  telescoping  or  the  gradual  shifting 
of  one  segment  within  another  until  it  is  partly  or  entirely  concealed. 

The  skeleton  covering  the  body  is  generally  considered  to  be  a  secre- 
tion from  the  outside  living  layer  of  cells,  the  hypodermis.  This  secre- 
tion gradually  hardens  on  exposure 
to  the  air,  providing  the  support 
necessary  for  the  soft  parts  within. 
Chemically  it  consists  of  chitin 
(Ci6H26N2Oio),  which  remains  thin 
and  flexible  at  the  movable  joints 
and  wing  articulations,  but  else- 
where becomes  thicker  and  usually 
darker  in  color.  Here  and  there 
over  its  surface  are  impressed  lines 
like  scratches,  very  definite  and 
fixed  in  position  in  most  insects, 
and  these  are  termed  sutures,  and 
are  of  great  use  as  landmarks  in 


ITJX.p. 


lab.p. 


FIG.  11. — Front  view  of  head  of  a  Grass- 
hopper showing  a  hypognathous  head ;  ant, 
antenna;  c.  e.,  compound  eye;  ch,  cheek;  cl, 
clypeus;/r,  frons;  lab.  p.,  labial  palpus ;lbr., 
labrum;  md,  mandible;  mx.  p.,  maxillary 
palpus;  o,  ocelli;  v,  vertex. 


description.      These    sutures  have 
such  an  arrangement  that  in  an 
ordinary  segment  of  the  body  its 
upper  surface  has  often  been  re- 
garded as  a  plate  or  sclerite,  the  notum;  one  at  each  side,  the  pleuron; 
and  one  beneath,  the  sternum.     These  plates  may  have   sutures  sub- 
dividing them. 

In  the  head  the  sutures  are  few  in  number,  and  only  a  few  plates  or 
sclerites  are  generally  in  evidence.  In  the  thorax  they  are  more  numer- 
ous, while  in  the  abdomen  often 
only  a  dorsal  and  ventral  sclerite 
for  each  segment  are  found. 
Occasionally  the  weakly  chitin- 
ized  areas  are  quite  large  (queen 
white  ant)  and  elastic.  Usually 
the  elasticity  of  these  places,  as 
for  example,  the  portions  con- 
necting the  segments,  is  rather 
slight.  Spines,  hairs,  scales  or 
other  structures  are  often  present 
°"  the  chitin,  sometimes  entirely 
(Original.)  concealing  its  surface  and  its 

sutures. 

The  heads  of  different  insects  vary  much  in  form  and  in  the  location 
of  the  mouth  (Fig.  11).  In  some  cases  this  is  on  the  underside  (see  Fig. 
10),  while  in  others  (Fig.  12)  it  is  practically  on  the  front.  Heads  with 


8 


APPLIED  ENTOMOLOGY 


the  mouth  beneath  are  called  hypognathous :  those  with  it  in  front  are 
prognathous. 

Structures  found  on  the  head  are  a  pair  of  antennae,  the  two  compound 
eyes,  ocelli,  and  the  mouth  parts.  On  the  thorax  are  the  wings  and  legs; 
and  on  the  abdomen  are  various  organs  such  as  the  ovipositor,  sting,  cerci, 
styli,  etc.,  present  in  some  cases;  absent  in  others. 


FIG.  13a. —  Different  forms  of  insect  antennse.      (Original.) 

Antennae  are  nearly  always  present.  They  are  usually  slender,  jointed 
and  therefore  more  or  less  flexible  organs,  varying  greatly  in  the  number  of 
segments  composing  them.  They  are  sometimes  very  short;  sometimes 
long;  often  thread-like;  sometimes  enlarged  near  the  tip;  in  many  cases 
with  fine  branches  either  on  one  or  both  sides,  so  that  they  resemble 
feathers  or  plumes;  rarely  they  fork;  in  fact  are  of 
many  forms  (Fig.  13) .  Sense  organs  are  present  on 
them  for  the  sense  of  touch,  and  probably  also  for 
smell  and  hearing,  at  least  in  some  cases. 

The  eyes  are  of  two  kinds.  There  is  a  pair  of  com- 
pound eyes,  each  of  which  is  a  group  of  similar  struc- 
tures which  usually  are  like  tall,  slender  pyramids  in 
form.  Only  the  bases  of  these  pyramids  show  on  the 
surface,  the  remainder  being  within  the  head.  The 
bases,  closely  pressed  together,  are  usually  more  or 
less  hexagonal,  and  their  outlines  can  often  be  easily 
seen  with  a  magnifying  glass.  They  are  called  facets, 
and  the  eyes  themselves  are  sometimes  termed  the 
facetted  eyes. 

The  other  kind  of  eyes,  called  ocelli,  may  be  absent, 
or  if  present,  may  vary  in  number  in  different  insects, 
three  being  perhaps  the  most  usual.  Each,  as  seen  from  the  surface, 
is  a  nearly  circular,  convex  spot  about  the  size  of  one  of  the  facets  of  a 
compound  eye.  It  may  be  larger  than  this,  but  is  never  equal  to  an 
entire  compound  eye  in  size.  In  some  cases  a  cluster  of  ocelli  or  of  the 
pyramids  of  the  compound  eyes  is  found,  not  closely  pressed  together 


FIG.  136. — An- 
tennse of  Cecropia 
Moth.  (Samia  ce- 
cropia  L.)  About 
twice  natural  size. 
(Original.) 


THE  INSECT:  ITS  EXTERNAL  STRUCTURE 


but  somewhat  separated,  and  such  groups  are  called  agglomerate  eyes. 
The  chitin  of  the  surface  of  the  body  is  transparent  where  it  covers 
the  surface  of  an  eye,  permitting  access  of  light  to  the  sensory  struc- 
tures within:  elsewhere  it  is  usually  pigmented  and  rather  opaque. 

The  mouth  parts  of  insects  vary  extremely  in  their  structure.  Appar- 
ently the  original  mouth  parts  were  for  biting  and  chewing,  and  this 
type  is  very  common.  In  some  groups,  however,  they  have  been  trans- 
formed into  a  sucking  apparatus.  Biting  mouth  parts,  being  the  more 


FIG.   14. — Three  types  of  insect  mandibles,  greatly  enlarged.     Somewhat  diagrammatic. 

(Original.) 

primitive  and  simple,  are  described  here,  while  sucking  mouth  parts 
having  been  differently  transformed  in  different  groups  will  be  taken  up 
in  connection  with  those  groups. 

In  front  of  (in  hypognathous  heads),  or  above  the  mouth  opening 
(prognathous  heads)  is  the  front  lip  or  labrum.     It  is  a  thin  flap,  hinged 
to  the  skeleton   of  the   head  and 
moves  forward  and  backward.    It 
is  often  more  or  less  divided  by  a 
central  notch  at  the  middle  of  its 
free  edge.     Its  inner  surface,  form- 
ing the  roof  of  the  mouth,  is  often 
called  the  epipharynx. 

At  the  sides  of  the  mouth  open- 
ing, immediately  behind  the  lab- 
rum,  is  a  pair  of  jaws,  the  mandibles. 
These  differ  greatly  in  form  in 
different  insects  (Fig.  14).  They 
are  often  stout,  heavy  structures 
with  crushing  faces  bearing  blunt 
projections  or  teeth ;  sometimes  they 
are  long,  curved  and  rather  slender. 
In  general  their  form  is  adapted  to  the  feeding  habits  of  the  insect. 

Immediately  behind  each  mandible  at  the  side  of  the  mouth  is  a 
second  appendage,  the  maxilla.  This  differs  markedly  from  the  mandible, 
being  much  weaker,  and  composed  of  a  number  of  pieces  (Fig.  15).  The 
tips  and  outer  internal  margins  of  the  maxillae  usually  bear  numerous 


FIG.  15. — Two  types  of  insect  maxilla 
greatly  enlarged.  Somewhat  diagrammatic. 
(Original.) 


10  APPLIED  ENTOMOLOGY 

spines  or  hairs,  but  this  condition  varies  according  to  the  nature  of  the 
food  of  the  insect.  Attached  on  the  outer  side  of  each  maxilla  not  far 
from  where  the  latter  articulates  with  the  head,  is  a  sort  of  tiny  antenna- 
like  structure  consisting  of  from  one  to  six  (usually  five)  segments,  which 
is  called  the  maxillary  palpus.  The  function  of  the  maxillae  appears  to  be 
to  hold  and  retain  the  food  in  the  mouth  while  it  is  being  worked  upon 
by  the  mandibles,  and  also  to  aid  these  in  breaking  it  up.  The  presence 
of  sense  organs  on  the  maxillary  palpi  suggests  that  these  are  possibly 
concerned  with  the  sense  of  smell.  Both  mandibles  and  maxillae  move 
sideways. 


FIG.    16. — Two    types    of    insect    labium    much    enlarged.       Somewhat    diagrammatic. 

(Original.) 

Behind  the  maxillae  and  closing  the  mouth  opening  behind,  is  the 
hinder  lip  or  labium  (Fig.  16).  This  was  evidently  once  a  pair  of  jaws 
somewhat  similar  to  the  maxillae,  but  with  no  mouth  cavity  between  to 
separate  them,  their  inner  edges  have  grown  together  to  varying 
degrees  in  different  insects.  In  some,  only  one  or  two  of  the  pieces 
nearest  the  head  have  fused:  in  others,  fusion  all  the  way  to  the  tip 
has  been  accomplished,  and  all  intermediate  stages  also  occur,  thus 
producing  a  structure  which  now  moves  forward  and  backward  like  the 
front  lip,  but  which  may  be  complete,  partially,  or  almost  entirely  cleft 
in  the  middle  line. 

Like  the  maxilla  the  labium  has  a  palpus  on  each  side  arising  from 
near  its  base,  and  composed  of  three  (rarely  four)  segments.  The  func- 
tion of  these  labial  palpi  appears  to  be  similar  to  that  of  the  maxillary 
palpi. 

Near  the  base  of  the  labium  on  its  inner  or  mouth  side  there  is  fre- 
quently a  fleshy  swelling  more  or  less  covered  by  bristles  or  hairs,  which 
is  called  the  hypopharynx,  lingua  or  tongue.  It  varies  greatly  in  size 
and  form. 

The  thorax  has  its  three  segments  usually  quite  clearly  marked. 
Each  segment  bears  a  pair  of  legs,  but  the  prothorax,  or  first  of  the 
three  behind  the  head,  bears  no  wings.  On  the  second  or  mesothorax, 
and  on  the  third  or  metathorax,  both  wings  and  legs  occur  in  the  majority 


THE  INSECT:  ITS  EXTERNAL  STRUCTURE 


11 


of  insects.  There  is  a  tendency  in  some  groups,  carried  farthest  in  the 
higher  Hymenoptera,  for  the  first  segment  of  the  abdomen  to  consolidate 
more  closely  with  the  metathorax  than  with  the  second  abdominal  seg- 


FIG.  17. — Different  forms  of  insect  legs.  A,  Cicindela  sexguttata  Fab.  (beetle);  B, 
Nemobius  fnsciatus  De  G.  (cricket)  hind  leg;  C,  Stagomantis  Carolina  L.  (Mantis)  fore  leg; 
D,  Pelocoris  femoratus  P.  B.  (carnivorous  bug)  fore  leg;  E,  Gryllotalpa  borealis  Burm. 
(mole  cricket)  fore  leg;  F,  Canthon  Icevis  Dru.  (a  digging  beetle)  fore  leg;  G,  Phanceus 
carnifex  L.  (a  digging  beetle)  fore  tibia  and  tarsus  of  female;  H,  same,  fore  tibia  of  male; 
/,  Dytiscus  fasciventris  Say,  male  (water  beetle)  fore  leg;  C,  coxa;  /,  femur;  s,  spine;  t, 
trochanter;  tb,  tibia;  ts,  tarsus.  (From  Folsom.) 

ment,  which  in  such  cases  is  often  slender  and  gives  thereby  a  semi- 
detached appearance  to  the  rest  of  the  abdomen,  as  though  the  line  of 
division  between  thorax  and  abdomen  were  at  that  place  instead  of 


12 


APPLIED  ENTOMOLWY 


ib 


farther  forward.  The  first  abdominal  segment  when  seemingly  more  a 
part  of  the  thorax  than  of  the  abdomen  is  called  the  median  segment  or 
propodeum. 

The  three  pairs  of  legs  may  be  quite  similar,  or  differ  widely,  according 
to  the  uses  to  which  they  are  put.     In  running  and  walking  insects  they 
are  usually  most  similar;  but  when  for  example,  the  fore  legs  are  used 
for  capturing  other  insects,  their  form  will  depart  greatly  from  that  of  the 
others.     The  jumping  power  of   the  grasshopper  is 
due  to  the  great  development   of   its   hind   legs   as 
compared  with  its   others.      Different   types  of  legs 
are  shown  in  Fig.  17. 

Whatever  may  be  the  variations  in  form  and 
details  of  the  legs,  all  are  composed  of  a  definite 
number  of  pieces  or  segments,  connected  by  hinge 
joints  so  arranged  that  by  combining  the  motions  of 
these,  a  leg  can  be  placed  in  nearly  any  position 
desired. 

The  leg  (Fig.  18)  is  composed  of  a  coxa,  a  tro- 
chanter  (two  in  a  few  cases),  a  femur,  a  tibia  and  a 
tarsus.  The  last  is  really  not  a  single  segment  but 
a  row  of  from  one  to  five,  small,  and  on  the  whole 
rather  resembling  each  other. 

The  coxa  is  the  segment  which  articulates  with 
the  body,  frequently  partly  lying  in  a  more  or  less 
cup-shaped  hollow  of  the  latter.  It  may  be  short  or 
long,  is  generally  freely  movable  on  the  body,  and 
powerful.  The  trochanter  is  usually  small  and  may 
not  be  visible  on  all  sides  of  the  leg.  It  is  followed 
by  the  femur,  generally  the  largest  and  stoutest,  but 
not  often  the  longest  leg  segment.  The  tibia  is  in 
most  cases  quite  long,  more  slender  than  the  femur, 
and  often  provided  with  downwardly  projecting 
spines  or  other  structures  which  are  of  assistance  to 
the  insect  in  climbing  plant  stems  and  other  objects, 
to  help  prevent  slipping.  The  tarsal  segments  are 
generally  rather  small,  short,  tend  to  be  broadest  at  their  outer  ends,  and 
vary  greatly  in  details  of  structure.  At  the  end  of  the  last  a  pair  of 
claws  is  generally  found,  and  between  them  a  sort  of  pad  or  cushion,  the 
pulvillus.  Sometimes  there  are  three  of  these,  in  which  case  the  outer 
ones  are  called  the  pulvilli  and  the  middle  one  the  empodium.  Where 
the  tarsi  are  reduced  to  a  small  number  of  segments,  only  one  claw  may 
be  present. 

The  wings  are  chitinous  outgrowths  from  the  body  which  vary  much 
in  size  and  form  in  different  insects.     Each  consists  of  two  delicate 


FIG.  18.— Leg  of  a 
Beetle  showing  parts. 
c.  coxa,  cl,  claws;  /, 
femur;  s,  spine  or 
spur;  ?M5,  tarsal  seg- 
ments; tb,  tibia; 
tr,  trochanter.  (From 
Folsom.) 


THE  INSECT:  ITS  EXTERNAL  STRUCTURE 


13 


membranes  in  contact  with  each  other  except  along  certain  lines  (Fig, 
19).  Along  these  lines  each  membrane. thickens  and  also  rises  above  the 
general  surface,  so  that  if  the  two  membranes  could  be  separated  and 
examined  from  the  inner  surface,  they  would  appear  uniform  except  for 
grooves  with  thickened  sides  and  bottoms,  running  here  and  there. 


FIG.  19. — Diagram  of  cross-section  of  an  insect  wing  showing  the  two  membranes 
somewhat  separated  and  the  ways  in  which  the  veins  are  formed.  (Modified  from  Wood- 
worth.) 

When  the  membranes  are  brought  together  again,  these  grooves  com- 
bining form  hollow  rods  which,  being  stronger  than  the  rest  of  the  mem- 
brane, serve  as  its  support  and  hold  it  stiff.  These  hollow  rods  are 
usually  called  veins  or  nerves,  though  they  are  nothing  of  the  sort. 
The  main  and  largest  veins  arise  at  the  base  of  the  wing  and  extend 
outward,  diverging  as  they  go,  and  some  branch  several  times  before  they 

/A 


~om. 


0.77L 


177, 


d.an 


FIG.  20. — Diagram  of  the  margins  and  veins  in  the  wings  of  moths.  A,  apex;  a.  an, 
anal  angle;  c,  costa;  c.c.,  closed  cell;  /,  frenulum;  i.n,  inner  margin;  o.m,  outer  margin;  v, 
vein.  (Original.) 

reach  the  wing  margin  (Fig.  20).  Cross  veins  also  occur,  connecting  the 
radiating  main  veins  or  their  branches.  Areas  of  membrane  between 
veins  are  termed  cells  and  where  entirely  surrounded  by  veins  are  called 
closed  cells.  These  may  be  relatively  few  or  many,  according  to  the 
number  of  veins  and  their  branches  present.  The  arrangement  and 
number  of  the  chief  veins  and  their  branches  are  of  importance  in 
identifying  insects. 


14  APPLIED  ENTOMOLOGY 

There  is  usually  a  point  or  tip  called  the  apex,  somewhere  along  the 
margin  of  the  wing,  though  frequently  the  outline  is  so  rounded  that  the 
exact  apex  is  uncertain.  The  front  margin  of  the  wing  from  where  it 
joins  the  body  to  where  the  edge  begins  to  turn  backward  (in  an  extended 
wing)  is  called  the  costa. 

Wings  are  entirely  absent  in  some  groups  of  insects,  and  it  is  probable 
that  these  are  the  direct  descendants  of  the  earliest  forms,  before  wings 
were  developed.  In  other  cases  where  they  are  absent  this  is  associated 
with  a  parasitic  life  where  wings  might  be  a  distinct  disadvantage,  or 
with  peculiar  habits  which  would  render  them  useless  or  even  inconvenient, 
and  in  such  cases  they  appear  gradually  to  have  become  lost.  In  the 
flies  the  hinder  pair  is  modified,  forming  small  structures  not  wing-like, 
called  halteres. 

The  abdomen  does  not  usually  show  great  differences  in  its  seg- 
ments except  those  near  the  hinder  end,  which  may  be  modified  for 
various  purposes.  Generally  a  dorsal  plate  and  a  ventral  plate  are  the 
only  two  skeletal  plates  evident  in  a  segment.  Small  openings,  usually 
a  pair  in  each,  or  at  least  in  most,  of  the  segments  are  the  openings  of  the 
breathing  organs,  and  these  also  occur  on  some  of  the  thoracic  segments 
where  they  are  ordinarily  less  noticeable  than  on  the  abdomen. 


FIG.  21. — Larva  of  Ceeropia   Moth  showing  abdominal  legs.     Two-thirds  natural  size. 

(Original.) 

Legs  are  very  rarely  present  on  the  abdomen  in  adult  insects,  but  are 
often  found  in  the  earlier  stages  (Fig.  21).  At  the  end  of  the  abdomen 
in  the  females  of  those  insects  which  lay  their  eggs  within  objects,  is  a 
combination  of  pieces  known  as  an  ovipositor.  It  usually  consists  of 
about  three  pairs  of  parts,  long  or  short,  slender  or  stout  as  the  case  may 
be,  for  the  purpose  of  making  a  hole  or  sawing  a  slit  in  the  object  in  which 
the  eggs  are  placed  and  in  guiding  the  eggs  into  the  hole  thus  made.  In 
one  group  which  has  apparently  changed  its  habits  and  no  longer  needs 
to  make  holes  for  egg  laying,  the  ovipositor  being  unnecessary  for  this 
purpose,  has  been  transformed  into  a  sting. 

A  pair  of  many-segmented,  antenna-like  structures,  sometimes  short, 
sometimes  long  may  occur  at  the  end  of  the  abdomen,  and  these  are 
called  cerci.  They  probably  serve  as  organs  of  touch,  and  possibly  also 
of  smell  in  some  cases. 


CHAPTER  III 
THE  INSECT:  ITS  INTERNAL  STRUCTURE 

Few  of  the  internal  structures  of  insects  are  of  any  great  importance 
from  the  standpoint  of  control  methods,  but  some  knowledge  of  them 
and  their  arrangement  is  desirable. 

Digestive  Organs  (Fig.  22). — The  alimentary  canal  extends  from  the 
mouth  through  about  the  center  of  the  body  to  the  anus  at  the  hinder 
end.  In  those  insects  whose  food  is  most  concentrated  (Fig.  23),  it  is 
in  its  simplest  form  and  is  but  little  if  any  longer  than  the  body.  In 
those  which  feed  on  less  concentrated  food  (Fig.  24),  the  necessity  for  a 
greater  digestive  and  absorptive  surface  has  resulted  in  an  increase 
of  its  length  and  the  accommodation  of  this  within  the  body  by  the 
production  of  loops  and  coils. 


FIG.  22. — Diagrammatic  longitudinal  section  of  an  insect  to  show  the  arrangement  of  the 
internal  organs.     (After  Berlese.) 

In  the  embryo  the  alimentary  canal  forms  as  three  separate  sections 
which  connect  later.  One  of  these  is  an  ingrowth  from  the  surface  where 
the  mouth  is  to  be;  another  and  similar  ingrowth  occurs  where  the  anus 
forms;  and  a  third  forming  earlier  than  the  other  two,  arises  as  two 
masses  of  cells,  one  near  each  end  of  the  embryo,  which  move  inward 
and  toward  each  other,  unite,  and  surround  the  yolk.  Later,  when  this 
has  been  absorbed,  a  space  is  left  with  which  the  two  ingrowths  already 
mentioned  connect,  the  hollow  centers  of  all  three  joining  to  form  the 
tube  through  which  the  food  travels.  The  ingrowth  from  the  mouth  is 
usually  called  the  fore-intestine,  the  central  portion  the  mid-intestine, 
and  the  ingrowth  from  the  anus  the  hind-intestine.  The  first  and  last 

15 


16 


APPLIED  ENTOMOLOGY 


of  these  begin  to  grow  inward  from  the  surface  of  the  body  after  that 
surface  has  begun  the  formation  of  its  chitinous  exo-skeleton,  and 
accordingly  also  have  this  power,  and  line  the  inside  of  the  parts  of  the 
canal  which  they  form,  with  chitin.  In  that  portion  of  the  canal  termed 
the  mid-intestine,  however,  this  power  does  not  appear  to  be  present,  and 
the  mid-intestine  is  without  this  lining. 


FIG.  23. — Alimentary  canal  of  a  Carnivorous  Beetle,  ad,  anal  glands;  cd,  stomach; 
ed,  hind  intestine;  in,  crop;  k,  head  and  mouth  parts;  oe,  oesophagus;  pv,  pro  veil  triculus; 
r,  rectum;  vm,  malpighian  tubes.  (Modified  from  Lang's  Lehrbuch.) 

The  mid-intestine  forms  the  stomach  of  the  adult  insect;  the 
fore-intestine  forms  those  parts  of  the  alimentary  canal  from  the  mouth 
to  the  stomach;  and  the  hind-intestine  those  from  the  stomach 
to  the  anus.  Each  of  these  sections  may  sometimes  have  portions 
differing  in  structure,  producing  a  greater  or  lesser  number  of  subdivisions. 
Thus  the  fore-intestine,  by  differences  of  structure,  may  sometimes  con- 
sist of  a  mouth  cavity,  oesophagus,  crop  and  proventriculus :  the  stomach 
may  develop  side  pouches  or  gastric  caeca;  and  the  hind-intestine  is  often 
separable  by  differences  of  structure  into  an  ileum,  colon  and  rectum. 

Lined  as  these  parts  are  by  chitin  which  often  bears  rough,  tooth-like 
projections  and  spines,  some  persons  have  suggested  that  in  insects  where 
these  structures  are  present  in  the  fore-intestine,  the  food  is  masticated 
more  thoroughly  and  mixed  with  digestive  juices  before  it  reaches  the 
stomach.  In  the  stomach  digestion  is  probably  completed  and  absorp- 
tion at  least  begun,  but  the  length  of  the  hind-intestine  in  many  insects 


THE  INSECT:  ITS  INTERNAL  STRUCTURE 


17 


suggests  the  idea  that  absorption  in  those  cases  has  not  been  completed 
when  the  food  leaves  the  stomach  but  continues  in  the  hind-intestine. 
Opening  into  the  mouth  is  a  tube  leading  to  the  salivary  glands,  which 
generally  lie  in  the  front  of  the  thorax  and  appear  to  have  a  similar  func- 
tion to  those  in  man.  In  some  cases  other  glands  for  different  purposes 
are  also  present  in  the  head  or  front  of  the  thorax  and  open  into  the 
mouth. 


ap 


FIG.  24. — Internal  anatomy  of  the  Honey  Bee  showing  alimentary  canal,  tracheal  and 
nervous  systems,  ce,  compound  eye;  hi,  hind  intestine;  hs,  honey  sac;  It,  lateral  trachea 
(enlarged);  mt,  malpighian  tubes;  rg,  rectal  glands;  s,  stomach;  sp,  spiracles.  (Modified 
from  LeuckarCs  Wandtafeln.) 

Some  of  the  poisons  used  in  control  measures  are  swallowed  by  the 
insect,  passing  to  the  stomach  and  there  are  dissolved  by  the  digestive 
juices.  Thus  dissolved,  they  set  up  inflammation  of  the  stomach  walls 
and  finally  cause  death.  Poisons  acting  in  this  way  are  called  "  stomach 
poisons. " 

Breathing  Organs. — Respiration  in  insects  is  accomplished  by  a 
method  which  is  nearly  unique.  The  oxygen  needed,  instead  of  being 


18 


APPLIED  ENTOMOLOGY 


drawn  into  lungs  and  there  being  taken  up  by  the  blood  and  carried  to 
the  parts  of  the  body  where  it  is  needed,  as  in  man,  is  carried  directly 
to  those  parts  by  a  system  of  air  tubes  which  open  along  the  sides  of 
the  body  (Fig.  25) .  Here  the  air  enters  the  tubes  and  proceeds  through 
them  to  where  it  is  utilized.  The  openings  by  which  the  air  enters  are 

called  spiracles,  and  these  occur  in  pairs 
on  some  of  the  thoracic  and  most  of  the 
abdominal  segments,  varying  somewhat 
in  number  and  in  position  on  the  seg- 
ment in  different  insects.  The  spiracles 
often  have  valves  by  which  they  can  be 
more  or  less  completely  closed  at  will. 

Each  spiracle  opens  into  a  short  tube 
or  trachea  which,  with  the  others  of 
that  side,  soon  joins  a  similar  tube  run- 
ning along  the  side  of  the  body  and 
quite  close  to  its  surface.  From  these 
longitudinal  tracheae,  branches  pass  off 
in  various  directions,  and  in  turn  branch 
again  and  again  until  every  part  of  the 
body  is  reached  by  its  air  supply.  The 
tracheae  frequently  enlarge  here  and 
there,  forming  so-called  air  sacs. 

The  tracheae  are  lined  by  chitin  con- 
nected .with  that  of  the  surface  of  the 
body.  In  these  tubes,  however,  it  is 
formed  with  spiral  thickenings  which  act 
like  a  spring,  keeping  the  tracheae  open 
when  not  under  pressure.  There  is 
probably  considerable  pressure  on  them 
in  different  places  by  the  movements  of 
various  parts  of  the  body  in  walking 
and  other  activities,  as  well  as  by  regular 
respiratory  movements,  and  the  resulting 
temporary  variations  in  diameter  aid  in 
the  circulation  of  air  in  these  tubes. 
Not  only  are  the  tracheae  of  use  in  carrying  oxygen  to  all  parts  of  the 
body,  but  they  also  receive  the  carbon  dioxid  gas  produced  by  the  activi- 
ties of  the  cells  and  permit  it  to  escape  through  the  spiracles  from  the 
body,  thus  performing  both  of  the  functions  which  the  blood,  so  far  as 
gases  are  concerned,  accomplishes  in  man.  Blood  then,  in  insects,  does 
not  (except  in  a  few  cases  perhaps)  have  a  respiratory  function. 

The  destruction  of  insects  by  fumigation  is  accomplished  by  the  sub- 
stitution of  a  gas  destructive  to  life,  for  the  air,  and  this  gas  enters  the 


FIG.  25. — Diagram  showing  ar- 
rangement of  the  main  tracheal  tubes 
in  an  insect,  a,  antenna;  b,  brain; 
I,  leg;  n,  nerve  cord;  p,  palpus;  s, 
spiracle;  st,  branch  from  main  lateral 
trunk,  t,  to  spiracle;  v,  ventral  branch; 
vs,  visceral  branch.  (After  Kolbe, 
from  Folsom.) 


THE  INSECT:  ITS  INTERNAL  STRUCTURE  19 

spiracles  and  follows  along  the  tracheae  to  the  living  tissues,  which  take 
it  in  place  of  the  oxygen  usually  received  in  this  way,  and  are  killed. 

It  was  formerly  supposed  that  certain  materials  called  contact  in- 
secticides which  kill  insects  by  contact  with  their  bodies,  caused  death 
by  entering  the  spiracles  and  closing  them  up,  thus  producing  suffocation. 
This  has  now  been  proved  to  be  incorrect. 

Insects  which  in  their  early  stages  live  in  water,  cannot  of  course 
breathe  air  into  their  bodies  through  spiracles  during  that  period  of  their 
lives.  These  are  closed  in  such  cases  and  the  animal  obtains  air  usually 
through  special  structures  called  tracheal  gills.  These  will  be  described 
in  connection  with  the  insects  which  possess  them.  In  a  few  small 
water-inhabiting  forms,  the  chitin  covering  the  surface  of  the  body  is  so 
thin  that  oxygen  present  in  the  water  can  pass  directly  through  it  into 
the  body  and  to  the  parts  there  which  need  it,  and  carbon  dioxid  passes 
in  the  reverse  direction. 

Circulatory  Organs. — Insects  have  only  an  incomplete  system  of  blood  vessels. 
A  tube  lies  in  the  middle  of  the  body  close  beneath  the  back,  beginning  near  the 
hinder  end  of  the  animal  and  extending  forward  into  the  head  (Fig.  26).  In  the 
abdomen  this  tube  is  constricted,  forming  chambers,  and  the  chambered  portion 
is  called  the  heart.  There  is  a  pair  of  openings  on  the  sides  of  each  chamber 
through  which  blood  can  enter,  and  valves  there  which  prevent  its  going  out 
again.  The  walls  of  the  heart  contain  muscles  and  these  contract  one  after  the 
other,  forming  a  sort  of  wave  of  contraction  which  begins  at  the  hinder  end  and 
travels  forward.  Blood  in  the  heart,  being  unable  because  of  the  valves,  to  pass 
out  at  the  sides,  is  pressed  forward  by  this  contraction  wave,  and  at  the  front  end 
of  the  heart  finds  itself  in  a  tube  without  chambers  or  valves,  called  the  aorta, 
through  which  it  is  led  to  the  head  where  the  aorta  may  divide  into  a  few  short 
branches  or  may  be  unbranched.  In  either  case,  at  this  point  the  blood  pours 
out  of  it  into  the  body,  the  system  of  blood  vessels  coming  to  an  end.  There  is 
now  no  definite  and  particular  path  for  the  blood  to  follow,  but  it  would,  in  theory 
at  least,  remain  near  where  it  escaped  from  the  aorta,  or  gradually  pass  into  any 
spaces  it  might  find  unoccupied  between  the  different  structures  in  the  head. 
With  each  heart-beat,  however,  more  blood  is  poured  out  of  the  aorta,  increasing 
the  pressure  upon  that  already  in  the  head.  It  therefore  is  gradually  forced 
backward  and  to  other  parts  of  the  body,  each  particle  probably  taking  the  path 
where  there  is  least  resistance  to  its  passage.  In  this  way  a  general  backward 
direction  is  given  to  the  flow. 

As  it  approaches  the  heart,  another  influence  appears.  During  each  contrac- 
tion of  the  heart,  it  occupies  less  space,  which  leads  to  less  than  normal  pressure 
near  it,  and  blood  close  by  naturally  flows  closer  to  it.  Upon  its  expansion  again 
and  the  opening  of  its  valves,  the  direction  of  least  resistance  is  now  through  the 
valves  and  into  the  heart. 

As  the  blood  passes  back  through  the  body,  a  given  particle  may  at  one  circuit 
go  over  certain  organs  and  at  the  next,  over  entirely  different  ones.  All  the 
internal  organs,  however,  have  their  surfaces  bathed  by  blood  and  this  as  it 
passes  over  the  stomach  or  other  parts  of  the  alimentary  canal  will  pick  up  any 


20 


APPLIED  ENTOMOLOGY 


food  which  having  been  digested  has  passed  through  the  canal  walls.  Likewise 
in  passing  over  any  organ  needing  this  food,  it  is  given  up  to  those  organs.  The 
blood  therefore  serves  as  a  distributor  of  food  from  the  place  where  it  is  digested 
to  all  the  parts  which  need  it. 

We  have  already  seen  that  the  living  parts  of  the  body — the  cells — need 
oxygen,  and  as  the  result  of  their  activities  give  off  carbon  dioxid  gas,  but  that 
this  exchange  is  accomplished  by  the  aid  of  the  tracheae.  In  a  somewhat  parallel 
way,  the  cells  which  need  food  obtain  it  from  the  blood.  The  cells  by  their 


FIG.  26. — Diagram  showing  by  the  direction  of  the  arrows  the  general  course  of  the  blood 
flow  in  a  Dragon  fly  nymph,     a,  aorta;  h,  heart.     (Modified  from  Kolbe.) 

activities  produce  not  only  carbonic  acid  gas  but  also  waste  material  nitrogenous 
in  nature  which  must  be  removed  like  all  wastes,  from  the  body.  This  nitroge- 
nous waste  is  picked  up  at  the  cells  by  the  blood  and  carried  along ,  perhaps  for 
some  time  before  a  place  to  dispose  of  it  can  be  found.  Sooner  or  later,  however, 
a  particle  of  blood  containing  this  waste  material  will  wash  over  certain  structures 
called  Malpighian  tubes,  to  be  described  in  the  next  section,  and  the  cells  which 
form  these  tubes  have  the  power  to  collect  this  waste  material  from  the  blood  as 
it  flows  over  them,  thus  purifying  it. 

The  blood  itself  is  usually  a  colorless  (though  sometimes  yellowish,  reddish  or 
greenish)  fluid,  in  which  are  corpuscles  resembling  the  white  corpuscles  of  human 
blood.  It  appears  to  serve  to  carry  food  to  the  tissues,  and  waste  matter  from 
them,  and  therefore  has  no  need  of  structures  in  it  like  the  red  blood  corpuscles 
of  man,  the  work  of  which  in  insects  is  done  by  the  tracheae. 


THE  INSECT:  ITS  INTERNAL  STRUCTURE 


21 


Excretory  Organs. — The  organs  which  eliminate  the  nitrogenous  wastes 
from  the  body  and  correspond  in  function  to  the  human  kidneys,  are 
known  as  Malpighian  tubes.  These  are  blind-ended  tubes,  the  walls 
of  which  consist  of  a  single  layer  of  cells  surrounding  a  central  channel 
which  at  one  end  opens  into  the  hind-intestine,  usually  near  its  front, 
just  behind  the  stomach  (Fig.  27).  When  blood  containing  nitrogenous 
waste  matter  washes  over  the  outer  surface  of  a  Malpighian  tube,  the 
cells  of  which  it  is  composed  have  the  power  of  taking  this  matter  out  of 
the  blood  into  their  own  substance  and  passing  it  through  themselves  into 
the  channel  between  them,  down  which  it  moves 
until  it  enters  the  mid-intestine,  from  which  it 
is  finally  expelled  at  the  anus. 

The  Malpighian  tubes  may  be  few  or  many; 
long  or  short  (see  Figs.  22,  23,  24).  They  show 
a  tendency  to  collect  in  groups  and  to  unite  near 
the  hind-intestine,  so  that  their  outlets  into  this 
are  much  fewer  than  the  number  of  tubes.  It 
seems  possible  that  a  certain  amount  of  poison 
entering  the  body  by  way  of  the  stomach  can 
be  eliminated  by  the  Malpighian  tubes,  which 
may  explain  the  varying  degree  of  resistance  to 
such  poisons  by  different  insects. 

Nervous  System. — The  nervous  system  of  insects 
is  located  along  the  middle  line  of  the  body  quite 
near   its   under   surface    (Fig.    22).     As   in   animals 
generally,  it  is  composed  of  cells  and  fibres.     The 
former  are  for  the  most  part  gathered  together  in    greatly  enlarged, 
clusters  which  are  called  ganglia,  and  from  each  of    rlTca'na^ 
the  cells  in  a  ganglion,   one  or  more  nerve  fibres    (Modified  from  Gegenbaur.) 
pass  out,  either  to  connect  with  some  other  nerve 

cell  or  with  some  structure  of  the  body.     The  larger  nerves  are  really  bundles 
of  these  fibres  running  side  by  side  like  the  wires  of  a  telephone  cable. 

Apparently  each  segment  of  the  insect  body  once  had  a  nerve  ganglion,  but 
with  the  fusion  of  the  segments,  many  of  these  have  also  fused,  reducing  the 
separate  ganglia  in  adult  insects  to  a  smaller  number,  which  varies  in  different 
kinds.  This  fusion  has  been  produced  by  the  hinder  ganglia  moving  forward  until 
in  some  cases  none  are  found  in  the  abdomen.  Different  degrees  of  this  are 
shown  in  Fig.  28. 

Each  ganglion  is  connected  to  the  one  in  front  and  the  one  behind  by  one  or 
two  bundles  of  nerve  fibres  which  are  called  commissures.  Each  consists  of 
numerous  fibres  and  these  taken  together  form  the  means  of  communication 
between  the  different  parts  of  the  system. 

In  the  head,  in  front  of  or  above  the  oesophagus,  is  the  largest  ganglion  of  the 
body,  called  the  brain,  produced  by  the  fusion  of  several  ganglia.  In  addition  to 
its  two  commissures,  which  connect  it  with  the  ganglion  next  behind,  it  has  nerves 
which  lead  to  the  eyes,  to  the  antennae  and  to  other  parts  of  the  front  of  the  head. 


FIG.  27. — Portion  of  the 
Malpighian   tube   of   a   fly, 
k,    cell 


22 


APPLIED  ENTOMOLOGY 


Below  or  behind  the  oesophagus  is  a  second  ganglion,  also  in  the  head,  called 
from  its  position  the  suboesophageal  ganglion.  As  the  oesophagus  lies  directly 
between  this  and  the  brain,  the  commissures  connecting  the  two  do  not  lie  close 
together,  but  separate  far  enough  to  permit  the  oesophagus  to  pass  between  them. 
The  suboesophageal  ganglion  besides  being  connected  with  the  brain  in  front, 
and  the  first  thoracic  ganglion  behind  it,  by  commissures,  sends  nerves  to  the 
mouth  parts  and  other  nearby- regions  of  the  head. 


FIG.  28. — Diagram  showing  various  degrees  of  concentration  forward  of  four  species  of 
flies.  A,  of  Chironomus  plumosus,  little  concentrated;  B,  Empis  stercorea;  C,  Tabanus 
bovinus;  D,  Sarcophaga  carnaria,  most  concentrated.  (After  Brandt,  from  Lang's  Lehrbuch.) 

The  thoracic  ganglia  may  be  more  or  less  separate  or  fused  and  may  have  fewer 
or  more  of  the  abdominal  ganglia  added.  Commissures,  however,  connect  all 
separate  ganglia,  and  these  also  send  out  nerves  to  all  the  parts  of  the  segments  to 
which  they  belong,  no  matter  what  their  final  location  may  be.  In  this  way,  the 
wings,  legs,  muscles  and  other  parts  receive  their  nerve  supply.  A  small  "sympa- 
thetic nervous  system"  also  present,  appears  to  be  concerned  chiefly  with  the 
nerve  supply  of  the  alimentary  canal  and  tracheae. 

Sense  Organs. — All  the  more  evident  senses  possessed  by  man  appear  to  be 
present  in  insects,  but  not  in  all  cases  in  the  same  individual.  Thus  some  cave- 
inhabiting  insects  have  no  eyes.  It  is  at  least  probable  that  insects  may  have 
other  senses  not  possessed  by  man. 

Reproductive  Organs. — Insects  are  of  distinct  sexes,  male  and  female. 
In  many  cases,  however,  individuals  occur,  incapable  of  reproduction, 
their  sexual  organs  not  having  become  fully  developed,  and  such  insects 
may  be  termed  neuters.  Most  of  these  appear  to  be  really  undeveloped 
females,  though  undeveloped  males  are  also  known.  They  are  found  in 
colonial  insects  where  division  of  labor  occurs,  as  in  the  honey  bee,  ants, 
termites,  etc.,  and  are  known  according  to  their  duties,  as  workers,  soldiers, 


THE  INSECT:  ITS  INTERNAL  STRUCTURE 


23 


or  by  other  names.     Conventional  signs  for  the  various  forms  of  insects 
as  a  convenience,  are :  cfmale;  9  female;  9  worker. 

In  the  female  (Fig  29)  the  eggs  are  produced  n  a  pair  of  ovaries  located  in 
the  upper  front  part  of  the  abdomen.  Each  is  a  cluster  of  ovarian  tubes  whose 
walls  are  cells.  Some  of  these  cells  grow  and  separate  from  the  others  to  lie  in  the 
central  cavity  of  the  tube  and  then  pass  downward,  growing  till  they  reach  its 
hinder  end,  which  connects  with  the  similar  ends  of  all  the  ovarian  tubes  of  that 
side  to  form  a  single  tube  called  the  oviduct.  This  extends  downward  and  back- 


cd. 


FIG.  29.  FIG.  30. 

FIG.  29. — Female  reproductive  organs  of  Honey  Bee  (Apis  mellifera  L.) ;  ag,  accessory 
gland;  o,  ovaries;  od,  oviduct;  pg,  poison  gland;  r,  rectum,  cut  off  and  end  bent  back;  sr, 
seminal  receptacle;  v,  vagina.  (Modified  from  Leuckart's  Wandtafeln.) 

FIG.  30. — Male  reproductive  organs  of  Honey  Bee  (Apis  Mellifera  L.) ;  ag,  accessory 
gland;  ed,  ejaculatory  duct;  s,  spermaries;  vd,  vasa  deferentia.  (Modified  from  Leuckart's 
Wandtafeln.) 

ward  around  the  side  of  the  alimentary  canal,  below  which  it  joins  with  a  similar 
oviduct  from  the  other  side  of  the  body  to  form  a  single  duct,  the  vagina,  which 
lies  below  the  alimentary  canal,  and  extends  backward  to  its  outer  opening  which 
is  located  in  most  cases,  in  front  of  the  next  to  the  last  abdominal  segment. 
Surrounding  this  opening  may  be  external  structures  (an  ovipositor)  for  the  pur- 
pose of  together  making  holes  in  some  object  (the  ground,  wood,  etc.)  in  which 
to  deposit  the  eggs.  A  side  pouch  (seminal  receptacle)  connected  with  the  vagina 
is  for  the  storage  of  the  sperms  which  fertilize  the  eggs;  a  gland  producing  material 
which  forms  the  egg  shell  and  is  known  as  the  shell  gland,  also  opens  into  this 
portion,  and  other  glands  similarly  connected  with  the  vagina,  may  also  be 
present. 


24  APPLIED  ENTOMOLOGY 

In  the  male  (Fig.  30)  the  arrangement  of  the  organs  closely  corresponds  to  that 
in  the  female.  A  pair  of  spermaries  or  testes  is  present  in  the  upper  front  part 
of  the  abdomen,  each  consisting  of  a  rather  closely-coiled  mass  of  tubes,  in  which 
the  sperms  are  produced.  The  tubes  on  each  side  unite  to  form  a  single  tube, 
the  vas  deferens.  These  differ  from  the  oviduct  usually,  in  being  much  longer 
and  coiled  or  twisted.  They  pass  downward  and  backward,  however,  and  unite 
on  the  middle  line  of  the  body  below  the  alimentary  canal,  forming  a  single  tube, 
the  ejaculatory  duct,  corresponding  to  the  vagina  in  position,  which  leads  back- 
ward to  an  opening  in  front  of  the  last  segment.  An  enlarged  portion  of  the  vas 
deferens  is  often  present,  for  the  temporary  storage  of  the  sperms,  and  is  termed 
the  seminal  vesicle.  Accessory  pouches  opening  into  the  ejaculatory  duct  appear 
to  be  in  part  at  least,  for  the  production  of  mucus  and  secretions  to  mix  with  the 
seminal  fluid. 


CHAPTER  IV 


THE  DEVELOPMENT  OF  INSECTS 

Most  insects  lay  eggs  which  hatch  after  a  longer  or  shorter  time  into 
the  young.  In  some  cases  the  egg  appears  to  be  retained  within  the 
body  of  the  parent  until  after  it  has  hatched,  and  then  the  young  are 
produced  in  a  stage  able  to  move  about.  Insects  in  which  this  is  true 
are  termed  viviparous,  the  others  being  oviparous. 

Insect  eggs  are  usually  very  small;  vary  greatly  in  form,  and  may  be 
laid  singly  or  in  clusters  (Fig.  31).  They  are  covered  by  a  chitinous 
shell,  the  chorion,  which  often  bears  markings  in  the  form  of  ridges, 


B 


FIG.  31. — Eggs  of  various  insects.  A,  butterfly;  B,  house  fly;  C,  chaleid  (Brucho- 
phagus);  D,  butterfly;  E,  midge;  F,  bug  (Triphleps) ;  G,  bug  (Podisus);  H,  Pomace  fly. 
All  much  enlarged.  (From  Folsom.) 

reticulations,  etc.,  and  frequently  they  are  also  colored.  At  one  place  on 
the  surface  is  a  minute  opening  or  group  of  openings  through  the  shell, 
called  the  micropyle,  believed  to  be  for  the  entrance  of  the  fertilizing 
sperm.  The  length  of  time  spent  in  the  egg  differs  in  different  insects 
from  a  few  hours  to  many  months,  and  in  some  cases  the  eggs  do  not 
hatch  until  the  second  season  after  they  are  laid. 

In  hatching,  the  shell  breaks  and  out  of  it  crawls  the  young  insect,  in 
the  majority  of  cases  quite  unlike  the  adult  it  is  to  become.  In  order  to 
reach  maturity  it  must  now  grow,  and  undergo  changes  in  structure  and 
appearance.  These  together  are  expressed  by  saying  that  most  insects 
in  order  to  become  adult  undergo  a  metamorphosis.  In  some  of  the 
simpler  insects,  a  few  changes  and  growth  only,  are  needed  to  make  them 
mature,  and  these  are  therefore  usually  grouped  together  as  the  Ameta- 
bola,  or  insects  having  practically  no  metamorphosis. 

25 


26  APPLIED  ENTOMOLOGY 

The  remaining  insects,  from  this  standpoint,  form  two  groups:  those 
which  on  hatching  show  some  resemblance  to  the  adults  and  reach  matu- 
rity by  a  certain  series  of  changes;  and  those  which  on  hatching  are 
totally  unlike  the  adults  and  attain  that  condition  in  a  different  way. 
These  groups  are  known  as  the  Hemimetabola  or  Heterometabola,  and 
the  Holometabola  respectively,  these  names  suggesting  the  amount  of 
metamorphosis  required  for  members  of  each  group  to  become  adult. 

A  member  of  the  group  Ametabola,  upon  hatching,  will  begin  to 
feed  and  grow.  Growth,  however,  is  restricted  because  the  insect  is 
enclosed  by  chitin  which,  while  elastic  to  some  extent,  at  least  at  its 
thinner  portions,  has  its  limitations  in  this  regard.  In  some  cases  the 
insect  is  able  to  reach  its  adult  size  within  the  chitin,  but  in  other  cases 
this  proves  impossible,  and  a  process  called  molting  takes  place.  This  is 
begun  by  pouring  out  of  fluid  by  the  outside  layer  of  living  cells,  the 
hypodermis,  between  it  and  the  chitin,  separating  the  two.  Next  a 
split  in  the  chitin  appears  somewhere,  usually  along  the  back,  and  the 
insect  crawls  out  of  its  skin,  i.e.,  molts.  It  is  now  soft  and  unrestricted  by 
an  outer  shell  and  grows  rapidly.  A  new  chitinous  shell  begins  to  appear 
and  is  completed  in  a  short  time  (within  a  day  or  so)  and  thereafter  only 
such  growth  is  possible  as  the  elasticity  of  the  new  shell  will  permit. 

In  most  of  the  Ametabola,  molting  as  thus  described  is  not  usual, 
the  shell  being  sufficiently  thin  to  stretch  the  amount  needed  for  growth 
to  adult  size,  though  sometimes  two  or  even  three  molts  may  occur. 
In  both  cases,  however,  the  reproductive  organs  appear  not  to  be  mature 
at  the  time  of  hatching,  and  only  gradually  become  so  during  the  period 
following.  In  a  few  cases  molting  seems  to  occur  at  intervals  throughout 
life. 

In  the  Hemimetabola  (or  Heterometabola)  the  young  insect  on  es- 
caping from  the  egg,  though  resembling  its  parent  to  some  extent, 
must  nevertheless  undergo  many  changes  in  structure  and  a  considerable 
increase  in  size  as  well,  before  reaching  maturity.  Thus  a  young  short- 
horned  grasshopper,  on  hatching,  will  need  to  grow  to  be  about  ten  times 
as  long  before  becoming  adult;  it  is  without  wings,  which  will  need  to  be 
developed;  its  reproductive  organs  are  not  mature  and  must  become  so, 
and  other  differences  occur.  All  of  these  must  be  transformed  into  their 
condition  in  the  adult,  and  to  accomplish  this,  energy  is  necessary.  In 
the  egg  the  energy  for  development  had  been  provided  by  the  yolk: 
after  hatching  the  young  insect  must  provide  it  by  gathering  food. 

The  young  insect  therefore,  soon  after  hatching  seeks  for  food,  and 
having  found  it  begins  feeding.  The  nourishment  thus  obtained  results 
in  growth  so  far  as  this  is  possible  within  a  shell  which  is  tightly  fitting 
and  only  to  some  degree  elastic.  When  no  further  growth  in  this  way 
can  occur  and  the  body  has  stored  within  it  all  the  materials  needed  for  a 
greater  increase  in  size,  it  proceeds  to  molt  in  the  manner  already  de- 


THE  DEVELOPMENT  OF  INSECTS  27 

scribed  for  the  Ametabola.  On  escaping  from  its  old  skin  or  shell,  how- 
ever, besides  a  rapid  increase  in  size,  changes  of  structure  also  occur, 
so  that  a  difference  in  appearance  now  becomes  evident.  These  changes 
must  be  produced  quickly,  as  the  hypodermal  cells  of  these  parts,,  as 
well  as  of  all  the  surface,  are  producing  a  new  chitinous  skin,  and  when 
this  has  once  hardened,  no  further  changes  and  little  further  growth  are 
possible.  Molting  then,  marks  the  beginning  of  a  brief  period — a  day, 
more  or  less — of  increase  in  size  and  of  changes  in  appearance,  these  last 
all  being  in  the  direction  of  making  the  young  insect  more  nearly  like  the 
adult  it  is  to  become.  When  the  new  shell  has  become  hardened  the 
insect  resumes  its  feeding. 

After  another  feeding  period  the  young  insect  is  again  confronted 
with  the  same  difficulties  as  before,  and  it  meets  them  in  the  same  way, 
by  molting,  and  immediately  thereafter,  before  its  new  shell  has  hardened 
it  seizes  the  opportunity  to  grow  and  change  its  appearance  further. 
Finally,  after  some  molt,  full  adult  size  for  the  insect  is  attained  and  all 
its  organs  have  also  fully  developed  and  matured,  producing  the  adult 
insect  itself. 

Thus  the  young  insect  becomes  an  adult  by  alternating  periods  of 
feeding,  with  brief  periods  of  molting,  following  which  growth  and  change 
take  place,  the  total  of  which  produces  the  adult. 

The  number  of  molts  and  consequent  opportunities  for  change  which 
occur,  varies  in  different  Hemimetabola.  There  may  be  only  two  or 
three  in  some  kinds:  five  is  perhaps  the  average  number  though  more 
are  not  uncommon,  and  21  are  known  to  occur  in  one  species. 

Certain  names  for  these  different  conditions  are  convenient  for  use. 

The  feeding  periods  between  the  molts  (or  ecdyses)  are  called  instars, 
so  that  the  progress  of  an  insect  from  hatching  to  adult  is  by  an 
alternation  of  instars  and  molts.  The  insect  itself,  from  hatching  until 
maturity  is  generally  called  a  nymph.  Figure  32  shows  the  changes  in 
size  and  appearance  of  a  grasshopper  after  each  molt. 

With  the  remaining  group  of  insects,  the  Holometabola,  while  there 
is  a  little  similarity  in  the  metamorphosis  to  that  in  the  Hemimetabola, 
there  are  also  many  differences. 

When  a  young  Holometabolous  insect  hatches,  it  in  no  way  resembles 
its  adult.  A  caterpillar  is  totally  different  in  appearance  from  the  butter- 
fly it  finally  becomes:  the  white  grub  in  the  earth  is  in  no  way  suggestive 
of  the  June  bug  (May  beetle)  into  which  it  transforms.  Nevertheless 
it  has  to  meet  the  same  problems  of  growth  and  transformation  to  the 
adult  condition  as  do  the  Hemimetabola,  and  uses  the  same  means  for 
accomplishing  the  needed  results,  viz.,  the  utilization  of  the  energy 
derived  from  its  food. 

Accordingly,  upon  hatching,  in  the  Holometabola,  a  feeding  period  or 
instar  comes  first,  followed  by  a  molt  and  growth.  At  this  point  the 


28   . 


APPLIED  ENTOMOLOGY 


story  of  the  metamorphosis  differs  from  that  of  the  Hemimetabola,  for 
after  the  molt  no  change  in  appearance  to  make  the  young  insect  more 
nearly  like  the  adult  takes  place.  It  may  be  different  in  some  regards 
besides  size,  from  what  it  was  before  the  molt,  but  these  differences  do  not 
increase  its  resemblance  to  what  it  finally  becomes.  This  holds  through- 
out the  feeding  period  of  its  existence,  so  that  after  three,  four  or  more 
molts,  a  caterpillar  is  still  a  cater.pilar,  a  grub  is  still  a  grub,  and  this  is 
equally  true  for  all  Holometabolous  insects.  Within  the  insect  during 
this  period,  however,  changes  not  perceptible  on  the  surface  are  taking 
place,  by  the  construction  of  portions  of  the  adult  which  are  forming  as 


FIG.  32. — Incomplete  metamorphosis  of  a  Grasshopper,  a,  first  nymphal  instar; 
b,  second  instar;  c,  third  instar  showing  beginning  of  wings;  d,  fourth  instar;  e,  fifth  instar; 
/,  adult.  Figures  not  drawn  to  same  scale.  (Modified  from  Packard's  Textbook 
of  Entomology  by  permission  of  the  MacMillan  Company,  Publishers.") 

buds  or  ingrowths  from  various  parts  of  the  body,  and  are  termed  imagi- 
nal  buds  (from  "imago,"  the  adult).  They  are  closely  compacted  and 
many  at  least  are  infolded  somewhat  like  buds,  becoming  finally  ready  to 
open  when  the  proper  time  comes.  And  during  its  feeding  instars,  the 
larva,  as  the  young  insect  in  the  Holometabola  is  called,  is  not  only 
storing  energy  from  its  food  for  its  growth  at  each  molt,  but  also  to  carry 
it  on  through  a  period  yet  to  be  described,  during  which  it  must  transform 
into  the  adult  condition  while  unable  to  feed  and  obtain  the  energy  needed 
for  this  purpose. 

After  a  varying  number  of  feeding  instars  and  molts,  the  young 
insect  or  larva  has  grown  sufficiently  and  has  stored  within  it  energy 
enough  to  carry  it  through  the  remainder  of  its  changes,  and  internally 
the  essential  parts  for  the  adult  condition  have  been  formed  as  far  as 


THE  DEVELOPMENT  OF  INSECTS  29 

possible  under  existing  conditions.  As  the  next  change  will  produce  an 
animal  practically  helpless  in  most  cases,  and  unable  to  protect  itself 
from  its  enemies,  its  next  step  is  to  find  as  much  protection  as  possible. 
Accordingly,  the  full-grown  larva  usually,  though  not  always,  leaves  the 
place  where  it  has  been  feeding  and  elsewhere  prepares  for  its  next 
change.  Many  larvae  begin  this  by  spinning  around  themselves  a 
thread  of  silk,  produced  by  glands  within  the  body  and  opening  to  the 
surface  on  the  lower  lip.  This  thread  is  spun  backward  and  forward  and 
around  the  body  until  it  sometimes  forms  a  complete  outer  covering, 
entirely  concealing  the  larva  within,  from  view.  This  case  or  cocoon 
appears  to.be  protective  in  its  function. 

Some  larvae  go  under  ground  for  this  change.  Here  a  cocoon,  as  such, 
seems  unnecessary,  but  after  digging  into  the  earth  a  few  inches,  the 
insect  forms  a  little  earthen  chamber  or  cell  in  which  to  lie,  and  generally 
lines  this  more  or  less  densely  with  silk,  probably  to  keep  the  earthen  walls 
from  falling  in  and  crushing  it.  A  larva  transforming  in  tunnels  in  wood 
where  it  has  fed,  may  make  a  partial  cocoon  with  more  or  less  of  the 
chewed-wood  fragments  mixed  in.  One  staying  above  ground  but  not 
in  tunnnels  or  otherwise  protected,  will  spin  more  or  less  of  a  cocoon 
as  already  described. 

The  completeness  of  the  cocoon,  however,  varies  greatly  with  differ- 
ent insects.  Instead  of  being  a  thick,  dense  wrapping  which  entirely 
conceals  the  insect,  it  may  be  so  scanty  that  the  animal  within  can  be 
seen  to  some  extent.  In  other  cases  it  is  merely  a  sort  of  network,  in  no 
degree  giving  concealment;  and  in  still  others,  a  few  scattered  threads  to 
hold  the  insect  in  place  are  all  that  represent  it.  Sometimes  hairs  from 
the  body  of  the  larva,  held  together  by  silk,  form  most  of  the  cocoon, 
and  in  the  case  of  butterflies,  only  threads  enough  to  attach  the  hinder 
end  of  the  body  at  the  place  where  it  is  to  transform,  and  to  form  a 
supporting  loop  around  its  middle,  the  ends  of  the  loop  also  being  fastened 
to  what  it  rests  on,  are  produced.  In  some  flies  the  larva  shrinks  within 
its  larval  skin  and  transforms,  this  skin,  now  called  a  puparium,  function- 
ing like  a  cocoon  (see  Fig.  33c). 

The  reason  for  such  variations  in  a  structure  presumably  formed  for 
the  purpose  of  protection,  can  only  be  guessed  at.  Possibly  in  the  course 
of  generations,  some  insects  found  less  need  of  this  than  others  and  gradu- 
ally reduced  it,  thereby  saving  the  vital  energy  so  much  needed  for  trans- 
formation, which  would  otherwise  be  expended  in  cocoon  making. 

Whether  the  larva  forms  a  dense  or  scanty  cocoon,  or  none  whatever, 
the  next  step  in  the  process  is  a  molt.  When  the  insect  escapes  from  this 
skin,  however,  a  great  change  in  its  appearance  is  evident,  and  it  is  now 
called  a  pupa  (Fig.  33a  and  6).  In  a  general  way  it  may  be  said  that  it 
has  at  this  one  molt  changed  more  than  half  way  to  its  adult  condition. 
This  is  due  in  part  at  least  to  the  unfolding  of  the  imaginal  buds  already 


30 


APPLIED  ENTOMOLOGY 


referred  to,  which  contribute  largely  to  form  the  new  surface  of  the  body 
in  which  head,  thorax  and  abdomen  are  evident,  as  are  also  the  antennae, 
legs,  stubs  of  wings  and  other  adult  structures.  Many  of  the  internal 
organs  of  the  larva  though,  were  necessary  for  use  till  the  last  moment 
before  it  became  a  pupa.  Then  too,  ths  arrangement  of  the  muscles, 
in  the  larva,  would  not  be  that  needed  by  the  adult.  Accordingly,  most 
of  the  internal  organs  now  gradually  break  down,  losing  all  their  earlier 
form  and  structure,  and  new  ones  to  meet  the  needs  of  the  adult  are  con- 
structed to  take  their  place. 


FIG.  33. — Different  types  of  pupation,     a,  pupa  obtecta  of  a  moth;  b,  pupa  libera  of  a  beetle; 
c,  puparium  of  a  fly.     a  and  b  about  natural  size;  c  much  enlarged.      (Original.) 

During  this  breaking  down  and  the  reconstruction  period,  the  pupa 
is  practically  helpless  in  most  cases,  hence  generally  the  need  for  the 
protecting  cocoon  or  earthen  cell  it  constructs. 

When  the  structure  of  the  adult  insect  has  been  completed,  another 
molt  takes  place,  the  pupa  skin  splitting  and  setting  free  the  insect.  If 
it  was  enclosed  in  a  cocoon  it  now  produces  a  fluid  which  sufficiently 
softens  the  silken  threads  so  that  it  can  push  its  way  out  and  it  escapes  or 
"emerges."  It  is  now  soft,  its  wings  are  only  partly  expanded,  as  in 
most  cases  there  would  be  no  room  for  full-sized  wings  in  a  pupa,  and 
because  of  its  reconstruction  there  is  considerable  waste  matter  in  its 
body.  The  insect  crawls  upon  whatever  it  may  find  to  hold  on  to,  expels 
the  waste  matter,  and  its  wings  begin  to  grow  rapidly.  Drying  out  also 
takes  place  and  in  a  short  time  (a  few  hours)  the  adult  thus  produced  is 
in  every  way  fully  matured. 

To  summarize  the  differences  in  metamorphosis  of  the  three  groups  it 
may  be  said  that  in  the  Ametabola  the  insect  hatches  from  the  egg  prac- 
tically in  an  adult  condition,  i.e.,  there  is  little  or  no  metamorphosis.  In 
the  Hemimetabola  the  insect  hatches  from  the  egg  in  a  form  somewhat 
resembling  the  adult  but  much  smaller.  It  becomes  adult  by  alternating 


THE  DEVELOPMENT  OF  INSECTS  31 

periods  of  feeding  with  molts,  at  which  times  growth  and  changes  bringing 
it  nearer  to  the  adult  occur,  the  last  molt  completing  the  growth  and  adult 
structure.  In  this  life  history  we  have  a  change,  but  as  there  was  a 
resemblance  to  the  adult  from  the  start,  the  change  to  it  (metamorphosis) 
is  only  an  incomplete  or  partial  one. 

In  the  Holometabola  the  insect  hatches  from  the  egg  in  a  form  totally 
unlike  the  adult,  and  while  feeding  periods  followed  by  molts  and  growth 
give  increase  in  size,  no  external  evidence  of  any  changes  making  the 
insect  more  like  the  adult  can  be  found.  These  changes  are  largely  made 
after  the  end  of  the  feeding  and  growing  periods  during  a  pupa  (generally 
quiet)  stage,  in  which  the  breaking  down  of  the  larval,  and  construction 
of  the  adult  structures  is  completed.  The  difference  between  the  larva 
on  hatching  and  the  adult  is  so  great  that  an  entire  change  (complete 
metamorphosis)  takes  place. 

It  should  be  evident  from  the  foregoing  that  when  the  adult  condition 
is  once  reached,  little  if  any  growth  is  possible  (except  in  rare  cases) 
and  that  the  belief  so  common,  that  "big  flies  grow  from  little  flies/' 
is  without  any  basis  of  fact. 

The  nymphs  of  the  Hemimetabola  appear  not  to  have  attracted 
sufficient  attention  to  have  received  any  special  common  names.  In 
the  Holometabola  the  larvae  of  various  groups  differ  greatly  in  appear- 
ance; many  are  large  and  noticeable  and  some  of  them  have,  as  a  result, 
received  special  names.  Larvae  of  butterflies  and  moths  are  commonly 
called  caterpillars;  those  of  beetles  are  usually  called  grubs;  those  of 
flies  are  called  maggots.  Larvae  found  boring  in  wood,  however,  whether 
they  will  become  moths,  beetles  or  other  insects,  are  uniformly  called 
borers. 

In  the  Hemimetabola  then,  the  stages  of  life  are:  egg,  nymph,  adult; 
in  the  Holometabola  they  are :  egg,  larva,  pupa,  adult.  Whether  or  not 
the  pupa  is  enclosed  by  a  cocoon  depends  upon  circumstances. 


CHAPTER  V 
LOSSES  CAUSED  BY  INSECTS:  NATURE'S  CONTROL  METHODS 

To  ascertain  how  much  man  loses  by  the  attacks  of  injurious  insects 
is  a  difficult  task.  The  destruction,  either  partial  or  entire,  of  his  crops 
both  growing  and  in  storage;  of  household  goods  and  of  food;  of  our 
forests  and  of  the  wood  cut  therefrom;  injuries  to  our  domestic  animals 
and  their  products:  these  and  other  injuries  can  be  more  or  less  accurately 
estimated.  But  when  we  consider  the  attacks  upon  man  by  disease- 
carrying  insects,  resulting  in  loss  of  time  from  productive  labor,  or  even 
by  death,  and  the  actual  costs  connected  with  illness,  the  problem 
becomes  extremely  complicated,  and  to  determine  how  much  financial 
loss  this  country  suffers  from  insects  is  a  matter  for  the  economist  as 
much  as  the  entomologist. 

Much  of  this  loss  W3  fail  to  appreciate,  never  having  had  a  season 
free  from  the  attacks  of  insects  which  might  serve  as  a  standard  for 
comparison.  If  we  could  once  have  such  a  year  entirely  insect  free, 
however,  the  difference  would  at  once  force  itself  upon  our  notice. 

Crop  Losses. — Careful  studies  of  the  crops  injured  by  insects  have 
now  extended  over  quite  a  term  of  years,  and  the  general  conclusion 
reached  is  that  in  an  average  year  with  no  unusual  attack,  a  crop  will 
generally  produce  only  about  nine-tenths  as  much  as  would  probably 
have  been  the  case  had  insects  not  been  present.  When  an  outbreak 
occurs,  this  will  decrease  production  below  that  point,  and  instances 
are  far  too  frequent  where  for  a  single  crop  of  some  kind,  production  has 
been  only  20  or  30  per  cent  of  the  normal,  and  many  cases  are  on  record 
where  in  some  localities  the  destruction  has  been  complete. 

This  estimate  covers  field  crops;  destruction  of  forests  and  forest 
products;  attacks  on  domestic  animals  and  their  products;  articles  in 
storage;  on  shade  trees,  shrubs  and  ornamental  plants;  on  farm  wood 
lots  which  are  not  included  with  the  forests;  on  household  goods  and  foods. 
With  fruit  and  truck  crops  the  destruction  and  injury  is  believed  to  be 
more  than  one-tenth  generally. 

Health  Losses. — A  number  of  serious  diseases  of  man  are  due  to 
insects  which  serve  as  carriers  of  the  disease-producing  organisms. 
Among  these  are  malaria,  the  typhoid,  typhus  and  yellow  fevers,  and  the 
bubonic  plague,  besides  others  of  less  importance.  Illness  with  any 
of  these  diseases  means  that  the  patient  is  not  only  unable  to  work  but 
is  an  actual  cause  of  outlay  for  nursing,  treatment,  and  possibly  death 
expenses  also.  With  hundreds  of  thousands  of  illnesses  from  these. 

32 


LOSSES  CAUSED  BY  INSECTS.  NATURE'S  CONTROL  METHODS    33 

diseases  each  year,  the  loss  of  time  from  productive  labor  is,  of  course, 
very  large,  and  the  country  is  that  much  poorer  than  it  should  be.  Death 
puts  an  end  to  any  further  production  by  those  concerned,  and  here 
also  is  a  loss  to  the  country.  It  has  been  estimated  that  the  loss  of 
labor  by  sickness  and  death,  caused  by  malaria  alone,  is  at  least  $100,- 
000,000,  and  by  all  insect-borne  diseases  is  over  $350,000,000  each  year 
in  the  United  States. 

In  addition,  there  are  many  places  in  this  country  where  the  soil 
is  rich  and  would  pay  well  if  cultivated,  but  where  man  cannot  live 
under  existing  conditions  because  of  the  presence  there  of  insects  and 
the  diseases  they  carry. 

Difficulties  in  Estimating  Losses. — To  fix  a  monetary  value  for  all 
this  destruction  and  injury,  however,  is  a  difficult  problem,  so  many  fac- 
tors enter  into  it.  It  cannot  be  denied  that  insect  attacks  result  in  a 
direct  reduction  of  wealth  to  the  country  as  a  whole;  that  whatever  food 
material  has  been  consumed  by  insects  is  not  available  for  consumption 
by  the  people,  is  self-evident;  and  that  if  on  account  of  a  resulting  scarcity 
of  any  food  the  consumer  pays  more  for  it,  he  is  thereby  paying  toward 
the  cost  of  the  ravages  by  the  insects.  The  producer  of  this  food  though, 
may  because  of  the  reduced  amount  available,  be  getting  as  much  or  even 
more  than  he  would  have  received  had  insects  not  destroyed  any  of  it.  In 
other  words,  while  the  destruction  of  any  crop  caused  by  insects  is  cer- 
tainly a  loss  to  the  nation  as  a  whole,  those  fortunate  individuals  who  suc- 
ceed in  raising  that  crop  may  receive  as  much  or  more  for  the  amount  they 
did  produce  than  would  otherwise  have  been  the  case.  On  the  other  hand 
the  man  who  starts  to  raise  such  a  crop  and  loses  a  large  percentage  of  it 
by  insect  ravages,  may  not  have  a  sufficient  amount  left  to  repay  him 
even  at  the  higher  prices,  for  his  expenses. 

It  is  evident  then,  that  insect  ravages  while  meaning  a  loss  to  the 
country  as  a  whole,  may  also  mean  either  a  loss  to  producers,  a  normal 
profit  because  of  a  higher  price  on  what  part  of  the  crop  they  have  been 
able  to  save,  or  even  a  better  profit,  due  to  higher  prices  than  could  other- 
wise have  been  obtained. 

No  crop  producer  can  as  yet  foretell  whether  he  in  any  given  year  will 
be  one  who  will  lose,  receive  a  normal  return,  or  do  better  than  usual  on 
any  of  his  crops.  He  can  only  be  prepared  for  insect  attacks  if  they  come, 
and  save  all  he  can  by  proper  methods  of  protection  and  repression,  know- 
ing that  the  vast  majority  of  the  people  will  do  little  or  nothing  in  this 
line  and  that  in  consequence  he  will  be  among  those  losing  least ;  will  have 
proportionally  more  to  sell,  and  that  he  will  therefore  receive  the  benefit 
of  any  higher  prices  coming  from  a  reduced  production. 

Against  what  he  will  gain  in  this  way  must  be  offset  the  cost  of  his 
protective  and  control  measures.  If  these  are  too  expensive  he  will  gain 
nothing,  but  in  most  cases  their  cost  is  small  as  compared  with  the  value 


34  APPLIED  ENTOMOLOGY 

of  the  product  saved,  and  such  measures  used  with  judgment  represent 
one  of  the  cheapest  and  most  successful  forms  of  crop  insurance. 

It  is  certain  that  the  time  will  never  come  when  protection  of  crops 
from  insect  ravages  will  ever  be  so  universal  and  successful  that  to  produce 
crops  will  not  pay,  for  with  our  increasing  industrial  population  to  be  fed 
the  demand  is  more  likely  increasingly  to  exceed  the  supply,  even  though 
every  crop  producer  should  finally  come  to  the  protection  of  what  he  raises, 
from  insects.  At  present  the  farmer  who  adopts  modern  methods  against 
insect  injuries  is  certain  in  any  term  of  years  to  raise  more  and  to  sell  at 
higher  prices  than  one  who  trusts  to  chance  or  "luck"  in  this  phase  of  his 
industry. 

Figures  on  Losses. — From  the  above  it  becomes  evident  that  no 
accurate  figures  as  to  the  losses  caused  by  insects  can  be  given.  We  can 
only  recognize  that  everything  produced  which  is  destroyed  by  these  pests 
is  thereby  lost  to  the  country  as  a  whole,  even  though  some  individuals 
may  profit.  To  value  this  destruction  we  have  only  the  prices  for  which 
crops  sell,  as  a  criterion,  and  the  point  has  already  been  brought  out  that 
if  the  tenth  destroyed  had  been  saved,  the  price  of  the  whole  might  have 
been  no  greater  than  it  was  for  the  nine-tenths  actually  produced.  Tak- 
ing this  unreliable  standard,  however,  in  order  to  get  some  slight  idea  of 
the  amount  of  destruction  ordinarily  caused  by  insects,  we  may  bring 
together  the  following  statement,  based  on  the  average  value  of  the  crops 
for  the  five  years  1913-1917  as  given  in  reports  of  the  United  States 
Department  of  Agriculture  and  from  other  sources. 

Field  crops $833,660,000 

Animals  and  their  products 431 ,450,000 

Forests,  forest  products  and  materials  in  storage 300 , 000 , 000 

Loss  by  human  disease  and  death 350,000,000 

Farm  wood  lots 100 , 000 , 000 

Extra  losses  on  fruit  and  truck  crops ? 

Shade  trees  and  ornamental  shrubs  and  plants ? 

Household  goods  and  foods ? 

Altogether,  if  we  may  accept  figures  based  on  the  assumption,  as  has 
been  indicated,  that  if  no  losses  had  occurred  the  value  of  the  whole 
would  be  at  the  same  rate  as  the  actual  price  for  what  was  obtained,  it  is 
safe  to  estimate  the  loss  in  the  United  States  due  to  injurious  insects  as 
being  not  far  from  two  billion  dollars  each  year.  How  nearly  correct  this 
is,  however,  no  one  can  tell,  so  many  factors  enter  into  the  problem. 

Causes  of  Increased  Injury. — Losses  to  crops,  forests  and  other  mate- 
rials are  increasing,  for  several  reasons.  Before  the  settlement  of  this 
country  there  were,  of  course,  native  insects  attacking  the  various  plants 
growing  here.  When  settlements  were  established  new  plants  were  intro- 
duced by  the  settlers  and  grown  in  greater  abundance  than  if  they  were 


LOSSES  CAUSED  BY  INSECTS:  NATURE'S  CONTROL  METHODS    35 

wild  and  scattered.  An  insect  finding  in  any  of  these  a  food  acceptable 
to  it,  would  at  once  also  find  a  more  abundant  supply,  and  a  rapid  multi- 
plication would  become  possible,  resulting  in  their  increase  to  injurious 
abundance.  A  second  factor  has  been  the  introduction  of  many  insects, 
from  foreign  countries.  In  the  United  States  such  forms  have  sometimes 
entirely  failed  to  maintain  themselves.  Unfortunately,  as  has  more  fre- 
quently happened,  they  have  found  all  conditions  favorable  to  a  rapid 
increase,  unchecked  by  their  enemies  which  in  most  cases  have  not  also 
been  brought  to  this  country  with  them.  A  third  factor  has  been  that 
with  the  increasing  occupation  of  this  country,  much  of  its  wild  bird  life 
has  either  been  destroyed  or  has  been  driven  away  from  the  neighborhood 
of  man.  Many  insect  feeders  among  birds,  once  quite  common,  must  now 
be  sought  in  remote  woodlands  and  thickets,  and  rarely  show  themselves 
near  settlements.  Some  kinds  have  adjusted  themselves  to  the  new 
conditions  and  among  these  may  be  mentioned  the  robin,  chipping 
sparrow,  blue  bird  and  a  few  others.  But  to  too  great  a  degree  the  insec- 
tivorous birds  are  becoming  either  fewer  in  number  or  afraid  to  visit  the 
settled  districts  where  cats  and  people  are  numerous,  even  though  in  such 
places  the  gardens  and  trees  may  be  thickly  populated  with  insects. 

With  modern  agricultural  methods  distinctly  favoring  a  rapid  in- 
crease of  insects  by  providing  an  enormous  acreage  of  a  single  crop;1  with 
an  addition  to  our  worst  native  pests  of  at  least  as  many  more  from  other 
countries,  which  have  escaped  their  enemies  by  coming  here;  and  with 
our  birds  becoming  less  effective  in  their  work,  it  is  only  natural  that  losses 
by  the  attacks  of  insects  should  be  great  and  increasing  in  importance. 

Control  by  Natural  Methods. — In  countries  undisturbed  by  man 
and  his  industries  it  is  probable  that  destruction  or  serious  injury  from 
insect  attacks  would  usually  be  rather  small,  particularly  in  a  series 
of  years.  The  saying  in  Physics  that  "Nature  abhors  a  vacuum" 
seems  to  be  paralleled  in  Biology  by  the  paraphrase,  "Nature  abhors 
extermination."  Accordingly,  insects  appear  to  be  "more  or  less  com- 
pletely held  in  balance  by  natural  factors,  some  of  which  may  be  briefly 
considered  here. 

Plants  of  various  kinds  form  the  food  of  most  of  the  insects  which 
we  regard  as  pests,  and  in  a  country  entirely  under  natural  conditions, 
plants  of  any  one  kind  are  liable  to  be  more  or  less  scattered,  no  large 
number  being  close  together.  Under  such  conditions  a  search  for  the 
proper  food  plant  is  necessary  to  an  insect  as  a  preliminary  to  egg- 
laying,  and  in  many  instances  these  may  be  too  scarce  to  provide  for  all 
the  insects.  In  any  case,  where  the  food  supply  is  scanty,  an  insect 

1  As  an  example  of  this,  apple  orchards  containing  thousands  of  trees  are  now 
common.  It  is  stated  that  one  year  in  a  single  valley  in  California,  there  were  three 
wheat  fields  each  containing  over  twenty  thousand  acres. 


36  APPLIED  ENTOMOLOGY 

species  feeding  wholly  on  that  kind  of  plant  will  be  more  rare  than  where 
its  food  is  abundant.  If,  on  the  other  hand,  there  is  an  abundance  of 
the  food  plant,  there  is  a  greater  probability  of  the  survival  of  more  of 
the  insects.  But  this  brings  its  disadvantages.  Increase  in  the  number 
of  the  insects  will  result  in  more  food  being  needed,  and  finally  this  will 
become  insufficient  and  will  be  followed  by  the  failure  of  many  to  find 
food,  death  resulting.  In  this  way  a  balance  may  be  finally  secured, 
though  it  will  not  be  permanent,  the  process  being  repeated  in  the 
subsequent  years. 

Weather  conditions  are  also  a  factor  in  Nature's  control.  Some 
insects  find  in  a  wet  season  conditions  favoring  the  survival  of  a  large 
proportion  of  those  which  appear,  while  for  others  such  a  season  produces 
heavy  mortality.  A  severe  winter  with  many  and  marked  fluctuations 
of  temperature  may  put  an  end  to  the  rapid  increase  of  some  species 
which  because  of  preceding  favorable  winters,  has  been  becoming  more 
abundant.  Other  meteorological  factors  also  enter  into  the  subject  of 
insect  control. 

Birds  and  other  animals  which  feed  on  our  insects  must  also  be  con- 
sidered in  this  connection.  When  insects  acceptable  to  these  animals  are 
abundant,  more  will  be  eaten  and  in  any  case  many  will  be  destroyed  in 
this  way.  Where  insectivorous  birds  have  an  abundant  food  supply 
more  will  survive,  which  will  result  in  more  individuals  to  be  fed.  Thus 
an  abundance  of  insects  may  lead  to  a  corresponding  increase  in  abun- 
dance of  their  enemies. 

Parasites  and  diseases  play  their  part  too  in  this  competition.  The 
more  abundant  an  insect  becomes,  the  more  food  is  thereby  available 
for  its  parasites,  and  fewer  of  these  will  fail  to  find  an  insect  to  attack. 
Finally  the  parasites  may  become  so  numerous  that  practically  all  the 
insects  of  the  kinds  they  attack  will  be  found  and  killed.  The  next 
generation  of  parasites  following  this,  will,  of  course,  consist  of  many 
more  individuals  than  the  one  preceding,  but  now  so  many  of  their 
food  insects  or  " hosts"  have  been  killed  in  producing  them  that  there  are 
practically  none  left,  and  most  of  these  parasites  die  for  lack  of  food. 
Thus,  under  these  conditions,  a  sort  of  " balance  of  Nature"  develops, 
and  though  the  scales  may  tip  first  to  one  side  and  then  to  the  other, 
this  balance  is  usually  preserved  if  periods  of  a  number  of  years  at  least, 
are  considered. 

But  when  man  with  his  many  lines  of  activity  appears  in  the  field, 
introducing  and  raising  millions  of  plants  of  the  same  kind  in  small 
areas,  instead  of  scattering  them  here  and  there,  thus  furnishing  enormous 
quantities  of  food  for  insects;  and  when  he  brings  in  many  pests  from 
foreign  countries,  no  matter  how  unintentionally,  which  in  their  new 
home  are  not  beset  by  the  foes  present  in  their  native  land;  and  when 


LOSSES  CAUSED  BY  INSECTS:  NATURE'S  CONTROL  METHODS    37 

his  manner  of  life  is  such  as  to  drive  away  birds  which  might  be  valuable 
aids  in  his  struggle  against  pests,  the  situation  changes  rapidly  for  the 
worse. 

Those  who  look  on  the  bright  side  are  confident  that  in  time  Nature 
will  reestablish  a  balance,  and  this  is  probably  true.  But  Nature  works 
in  centuries,  and  man  cannot  wait  so  long  for  results. 

Under  these  conditions  artificial  measures  as  contrasted  with  natural 
ones  must  be  taken  if  crops  are  to  be  raised,  food  obtained,  and  if  health 
is  to  be  preserved,  and  these  artificial  methods  for  the  control  of  injurious 
insects  need  to  be  known,  and  the  nature  of  their  action  understood. 


CHAPTER  VI 
ARTIFICIAL  METHODS   OF  CONTROL 

It  has  been  indicated  that  Nature  has  methods  for  the  control  of  any 
continued  undue  abundance  of  insects,  by  a  resulting  scarcity  of  food; 
by  weather  conditions;  by  insectivorous  birds  and  other  animals;  by 
parasites  and  diseases;  and  probably  in  other  ways  also.  But  it  seldom 
pays  to  wait  for  the  results  so  obtained,  as  they  generally  require  a  num- 
ber of  years  for  completion,  and  measures  which  may  be  termed  artificial, 
inasmuch  as  they  are  used  by  man,  also  have  their  value. 

These  measures  may  be  divided  into  two  groups,  viz.,  those  which 
aim  to  establish  conditions  unusually  favorable  to  the  plants  or  un- 
favorable to  the  insects;  and  those  which  attempt  either  to  poison  or 
otherwise  directly  kill  the  insects.  In  some  cases  perhaps,  a  given  treat- 
ment might  seem  to  belong  as  properly  in  one  of  these  groups  as  in  the 
other,  but  in  general  the  line  of  separation  is  quite  distinct. 

Whatever  the  method  and  its  effectiveness  may  be,  there  is  always 
the  cost  of  using  it  to  bear  in  mind.  When  this  cost  is  greater  than  the 
loss  would  otherwise  probably  amount  to,  it  is  evident  that  little  will  be 
gained  by  treatment,  except  that  in  such  cases  possibly,  omitting  it  for 
this  reason  one  year  may  result  in  such  an  increase  of  the  pest  as  to  pro- 
duce serious  results  the  following  season.  In  other  words,  treatment 
costing  more  than  the  probable  loss  may  sometimes  pay  as  a  sort  of  in- 
surance. In  general,  though,  in  every  case  where  insect  attack  occurs, 
the  estimated  cost  of  the  treatment  should  be  weighed  against  the 
probable  loss  without  it,  in  deciding  whether  to  treat  or  not. 

GENERAL  FARM  PRACTICES 

These  are  chiefly  methods  for  raising  crops  which  distinctly  increase 
their  vigor  and  growth  or  remove  conditions  favorable  to  insects. 
Healthy  crops,  clean  culture,  the  rotation  of  crops,  late  or  early  plowing, 
and  the  time  of  planting  are  the  chief  farm  practices  which  belong  here. 
Special  methods  for  particular  cases,  directed  more  with  reference  to  the 
insects  than  to  the  handling  of  the  plants,  such  as  hand  picking,  the  use 
of  repellents,  burning  insects,  heat,  trap  lanterns,  etc.,  may  also  be  in- 
cluded here,  leaving  the  measures  dealing  with  insects  by  the  use  of  poisons 
and  by  fumigation  for  later  consideration. 

38 


ARTIFICIAL  METHODS  OF  CONTROL  39 

Healthy  Crops. — In  the  majority  of  cases  a  vigorous,  thoroughly 
healthy  plant  is  not  only  better  able  to  withstand  insect  injury  but  is 
also  less  liable  to  attack  than  one  enfeebled  or  not  thriving  for  any  reason. 
Thorough  cultivation,  the  use  of  fertilizers  and  the  removal  or  repair  of 
injured  or  diseased  parts  or  plants  as  soon  as  these  appear,  will  aid 
greatly  in  insuring  the  desired  results. 

Clean  culture  is  also  an  important  factor.  Weeds  not  only  interfere 
with  successful  crop  growth  but  may  in  some  cases  at  least,  consume 
plant  food  in  the  soil  which  might  otherwise  be  utilized  by  the  crop, 
thus  reducing  its  vigor,  and  in  addition  they  provide  wintering  places 
for  many  insects.  Rubbish  left  on  a  field  after  the  harvest  often  serves 
the  same  purpose:  insects  frequently  find  protection  during  the  winter 
in  tall  grass  too  often  left  surrounding  the  trunks  of  fruit  trees,  and 
many  serious  pests  winter  close  to  the  ground  in  grass  fields.  Decaying 
fruits  and  vegetables  harbor  insects  and  should  be  composted.  Weeds 
should  therefore  be  killed  and  burned  and  the  grass  kept  down  in  or- 
chards. Burning  over  grass  fields  in  early  spring  in  the  Northern  states  at 
least,  choosing  a  time  when  the  dead  growth  is  dry  enough  to  burn  while 
the  living  parts  of  the  grass  are  still  so  wet  as  to  be  uninjured  by  the  heat 
is  often  a  valuable  way  in  which  to  destroy  many  pests  which  winter 
there.  Clean  culture  in  all  its  forms,  not  forgetting  fence-line  and  road- 
side growth  will  do  much  to  reduce  loss  by  insects. 

Crop  Rotation. — The  rotation  of  crops  often  has  an  important  bearing 
on  insect  control.  Any  crop  attacked  by  a  particular  species  of  insect 
should  not  be  followed  by  another,  either  of  the  same  kind  or  by  a  differ- 
ent one  which  is  also  fed  upon  by  that  species  of  insect.  How  far  this 
principle  can  be  carried  out  in  practice,  however,  is  a  different  matter. 
To  break  up  sod  land  and  plant  corn  for  the  first  crop  is  merely  to  follow  a 
mixture  of  grasses  with  a  single  kind  of  a  grass  and  from  the  standpoint  of 
insect  control  at  least,  is  unwise.  It  is  the  usual  practice  though,  and 
how  far  it  would  be  wise  to  depart  from  it,  planting  beans,  buckwheat  or 
perhaps  potatoes  instead,  is  a  question,  though  these  last-named  crops 
would  be  much  more  likely  to  be  free  from  insects.  The  entire  subject 
of  crop  rotations  which  are  satisfactory  from  the  standpoint  of  agri- 
culture and  are  also  correct  when  insect  problems  are  considered,  is  still 
in  a  far  from  settled  condition,  and  needs  prolonged  investigation. 

Plowing. — Many  serious  pests  winter  in  the  ground.  Fall  plowing 
after  they  have  formed  the  cells'  in  which  they  pupate  or  winter,  as  the 
case  may  be,  will  break  many  of  these  and  remove  the  protection  they 
give :  eggs  laid  in  the  ground  will  often  be  buried  so  deeply  that  the  larvae 
if  they  hatch  in  spring  will  be  unable  to  reach  the  surface.  Similarly, 
thorough  cultivation  in  the  summer,  where  it  is  possible,  besides  being 
good  for  the  crop,  has  an  injurious  effect  on  insects  there. 

In  some  cases  early  fall  plowing  gives  the  best  results :  in  others,  late 


40  APPLIED  ENTOMOLOGY 

fall  is  the  best  time.  Sometimes  disking  with  a  harrow  can  be  done 
where  plowing  cannot,  and  is  of  value. 

Time  of  Planting. — This  is  sometimes  of  importance  as  a  protection 
against  pests.  Thus,  in  general,  wheat  sown  after  September  20  will 
escape  the  attacks  of  the  Hessian  fly :  early  planting  will  often  give 
cotton  an  opportunity  to  obtain  the  greater  part  of  its  growth  before  the 
boll  weevil  has  progressed  far  in  its  ravages,  particularly  if  early  maturing 
varieties  of  cotton  are  planted.  It  follows  from  this  that  a  choice  of 
the  variety  to  plant  is  also  often  of  importance,  and  insect-resistant 
varieties  of  our  various  crop  plants  and  trees  should  be  selected  as  far  as 
any  are  known,  if  they  are  otherwise  satisfactory.  The  "  bugless  potato," 
while  perhaps  non-existent,  expresses  an  idea  which  should  be  kept  in 
mind,  and  resistant  varieties  of  plants  should  be  watched  for  and 
preserved. 

Trap  Crops. — In  some  cases  trap  crops  can  be  made  use  of  to  advantage. 
A  small  patch  of  kale  planted  in  the  fall,  or  of  mustard  planted  early  in 
spring  will  attract  the  Harlequin  cabbage-bugs  as  they  leave  their  winter 
quarters,  and  on  these  they  can  be  destroyed,  as  they  seem  to  prefer 
such  plants  to  the  young  cabbages.  Several  similar  cases  are  also  known 
where  trap  crops  work  well. 

Hand  Picking. — In  some  cases,  where  the  pest  is  large,  easily  seen, 
or  not  present  in  large  numbers,  hand  picking  is  the  easiest  method  of 
control.  Egg  clusters  are  often  of  such  a  color,  size,  or  have  such  notice- 
able features  that  they  are  not  difficult  to  find,  and  the  convenience  of 
destroying  several  hundred  eggs  at  a  time,  as  compared  with  killing  the 
same  numbar  of  insects  after  the  eggs  have  hatched  and  the  young  have 
scattered,  is  evident.  Larvae  feeding  in  groups  together  are  also  often 
most  easily  destroyed  by  hand  picking. 

Repellents. — Inert  materials,  such  as  air-slaked  lime,  flour,  or  even 
fine  road  dust,  thickly  spread  over  plants  will,  in  certain  cases,  act  as 
repellents,  driving  insects  elsewhere  to  a  greater  or  lesser  degree.  Car- 
bolic acid,  naphthaline,  oil  of  citronella,  and  other  materials  having  an 
objectionable  odor  act  as  repellents  to  some  insects. 

Trap  Lanterns. — These  have  been  quite  extensively  tested,  but  have 
failed  to  be  as  successful  as  was  expected.  Though  many  insects  are 
attracted  to  such  lights,  the  greater  number  are  found  to  be  beneficial, 
while  of  the  injurious  kinds  a  large  number  have  already  laid  their  eggs 
and  are  therefore  no  longer  of  any  importance,  and  most  of  the  serious 
pests  are  not  attracted  at  all.  On  the  whole  it  is  doubtful  if  the  use  of 
trap  lanterns  ever  pays. 

Burning  Insects. — Gasoline  torches  for  burning  egg  clusters,  cater- 
pillars, scale  insects,  etc.,  on  trees,  have  also  been  tried,  but  the  time 
necessary  to  kill  the  insects  in  this  way  is  often  long  enough  to  injure 
the  tree  where  the  blast  hits  it,  and  this  method  must  be  regarded  as  at 


ARTIFICIAL  METHODS  OF  CONTROL  41 

least  exposing  the  plant  treated,  to  the  risk  of  greater  injury  than  that 
caused  by  the  insects. 

Heat. — Heat  can  sometimes  be  used  to  advantage  for  the  destruction 
of  insects.  A  temperature  of  125°F.  is  enough,  if  maintained  for  3  or 
4  hr.,  to  kill  insects  infesting  grain,  seeds,  etc.,  and  also  almost  all  house- 
hold pests  at  least.  Where  heat  can  be  applied  in  this  way,  therefore,  it 
is  a  special  method  of  control  of  considerable  value. 

Miscellaneous  Methods. — Borers  in  trees  present  particular  difficul- 
ties, being  so  hard  to  reach,  and  cutting  them  out  by  hand  is  frequently  the 
best  control  method.  Protective  coverings  over  or  around  plants  may 
sometimes  be  used  to  advantage,  as  for  example,  netting  over  young 
cucumber  and  squash  plants.  Sticky  bands  placed  around  the  trunks  of 
trees  keep  insects  which  cannot  fly  from  crawling  up  to  the  leaves. 
Pieces  of  bark  or  boards  on  the  ground  near  plants,  under  which  insects 
may  crawl  for  protection  at  night,  as  some  do,  are  good  traps  for  such 
insects,  if  these  traps  are  visited  early  in  the  morning  and  the  insects 
destroyed  before  they  scatter  again  for  the  day.  Burlap  bands  around 
tree  trunks  attract  many  caterpillars  as  being  good  hiding  places  during 
the  day.  These  and  numerous  other  special  methods  for  the  control  of 
insects  are  made  use  of,  many  being  based  on  some  peculiarity  of  habits 
of  the  special  pest  for  which  they  are  used. 

Still  other  methods  will  be  considered  later,  in  connection  with  the 
insects  against  which  they  are  used. 

In  order  to  make  proper  use  of  the  above  methods  of  Farm  Practice, 
a  clear  understanding  of  the  life  and  habits  of  the  insect  to  be  controlled, 
must  be  had.  Failure  in  this  might  easily  lead  to  doing  just  the  wrong 
thing. 


The  control  of  insects  is  at  the  present  time  very  unequally  developed 
for  different  crops.  Naturally  the  insects  of  those  which  are  most 
valuable  have  been  most  carefully  studied,  those  of  less  importance 
having  been  given  much  less  attention.  Fruit  and  market-garden  crops 
have  a  high  value  and  the  insects  which  attack  them  have  been  carefully 
investigated,  though  the  area  they  cover  is  very  small  as  compared  with 
the  wheat  acreage  of  this  country,  for  example.  Trees,  bushes  or  other 
plants,  whether  growing  alone  or  in  rows  with  cultivated  land  or  grass 
surrounding  them  are  accessible  as  units  on  which  to  work,  but  a  10-acre 
field  of  clover,  wheat  or  any  other  crop,  is  a  totally  different  proposition. 
The  former  can  be  reached  in  all  its  parts  by  a  spray  or  other  treatment : 
a  wheat  plant  in  the  middle  of  a  field  may  need  treatment  but  to  reach 
it  would  probably  cause  a  greater  amount  of  injury  than  would  be  saved 
by  the  treatment. 

Field  crops  and  particularly  grain  crops  therefore,  present  distinct 


42  APPLIED  ENTOMOLOGY 

problems,  and  here  Economic  Entomology  and  Practical  Agriculture 
have  failed  to  work  as  closely  together  as  should  be  the  case,  and  our 
present  methods  for  controlling  field  crop  insects  are  less  effective  than 
with  most  others. 

The  same  thing  is  true  with  our  forests.  The  shade  tree  can  be 
sprayed  if  that  is  a  desirable  treatment,  but  the  spraying  of  forests  even 
if  practicable  from  the  standpoint  of  expense,  is  frequently  impossible 
because  of  the  nature  of  the  ground  on  which  the  forest  stands,  density  of 
growth  and  other  factors,  and  other  and  more  indirect  methods  of  insect 
repression  then  must  be  resorted  to. 


CHAPTER  VII 

t~- 

INSECTICIDES  IN  GENERAL:  STOMACH  POISONS 

Though  the  farm  practices  and  special  methods  outlined  in  the  pre- 
ceding chapter  are'  of  great  importance  for  the  control  of  insect  pests 
in  many  cases,  they  are  ineffective  and  cannot  be  made  use  of  in  many 
others.  Under  these  circumstances  other  methods  of  attack  must  be 
resorted  to,  and  in.  general,  insecticides  of  various  kinds,  fitting  the. 
particular  nature  of  the  injury  and  of  the  insect  causing  it  in  each  case, 
have  proved  successful.  Insecticides  are  substances  which  may  be 
placed  upon  a  plant,  or  elsewhere,  to  be  eaten  by  the  insect  and  which 
when  eaten,  kill  the  insect ;  or  materials  which  on  coming  in  contact  with 
the  body  of  the  insect,  kill  it  as  a  result  of  that  contact.  Poisonous 
gases  and  vapors  v/ould  also  be  included  as  insecticides,  as  thus  defined. 

CLASSES  OF  INSECTICIDES 

The  materials  used  as  insecticides  fall  into  two  general  groups:  (1) 
Those  which  are  placed  upon  the  food  eaten  by  the  insect,  swallowed 
with  it,  and  which  upon  entering  the  stomach  are  dissolved,  producing 
inflammation  and  finally  death.  Such  poisons  can,  of  course,  be  used 
only  for  insects  with  chewing  mouth  parts  which  bite  off  and  swallow 
solid  food,  sucn  as  pieces  of  leaves,  stems,  etc.;  (2)  Those  which,  when 
they  come  in  contact  with  the  body  of  an  insect  either  enter  the  spir- 
acles and  penetrate  their  chitinous  lining  and  kill  the  tissues  beyond; 
or  which  corrode  the  body;  daprive  it  of  oxygen;  or  by  softening  the 
coverings  over  the  body  (scale  insects)  cause  these  to  adhere  to  the 
plant  it  is  on,  killing  the  insect  in  any  case.  The  materials  of  the  first 
group  are  usually  called  stomach  poisons;  those  of  the  second,  contact 
insecticides.  The  latter  could  also  be  used  for  biting  insects  but  the 
difficulties  in  the  way  of  their  being  successfully  applied  are  such  that 
stomach  poisons  are  used  whenever  possible. 

In  reaching  the  insects  concerned,  either  with  stomach  poisons  or 
contact  insecticides,  the  methods  of  conveying  the  material  to  where 
the  insect  is,  and  of  an  even  and  thorough  distribution  of  it  are  important. 
Those  substances  which  are  solids  in  the  form  of  fine  powders  can  be 
blown  onto  the  tree  or  whatever  the  insect  may  be  on,  but  some  are 
liquids.  Accordingly,  "powder  guns"  for  spreading  the  poisonous 
dusts  have  been  used  with  considerable  success,  and  pumps  with  a  fine 
nozzle  at  the  end  of  a  line  of  hose  are  used  for  the  liquids. 


44  APPLIED  ENTOMOLOGY 

With  stomach  poisons,  however,  the  poison  is  not  necessarily  eaten 
by  the  insect  as  soon  as  it  falls  on  the  plant,  but  must  or  should  remain 
there  for  some  time,  as  the  insects  may  appear  during  a  period  of  several 
days  or  even  weeks.  During  this  time  much,  probably  most,  of  the 
poisonous  dust  would  be  blown  off  and  the  treatment  be  of  little  value. 
In  spite  of  this  difficulty,  much  successful  work  has  been  done  with  dry 
stomach  poisons,  and  they  have  many  advantages  over  sprays  under 
certain  conditions. 

It  has  been  found  that  when  stomach  poisons  are  mixed  with  water 
and  sprayed  onto  plants  in  the  form  of  very  fine  droplets,  the  spray 
appearing  like  a  fine  mist,  each  droplet  soon  dries,  leaving  behind  it 
the  poison  it  contains,  adhering  to  the  leaf,  where,  unless  washed  off  by 
•rain,  it  will  remain  a  long  time.  This  has  led  to  ths  general  adoption  of 
spraying,  both  with  stomach  poisons  and  contact  insecticides,  despite 
certain  difficulties  which  have  developed. 

STOMACH  POISONS 

Arsenic  is  the  basis  of  nearly  all  the  commonly  used  stomach  poisons, 
for  though  probably  more  than  50  materials  have  been  tested,  only  a 
few  have  proved  at  all  satisfactory,  and  with  two  or  three  exceptions, 
useful  only  under  special  conditions,  they  have  all  been  arsenical  com- 
pounds. It  would  seem  natural  under  these  circumstances  to  use 
common  white  arsenic  (As2Os)  as  the  stomach  poison,  it  being,  when 
pure,  100  per  cent  arsenic  (arsenious  oxid).  But  it  is  found  that  arsenic 
dissolves  to  some  extent  in  water,  and  that  thus  dissolved  it  destroys 
(" burns")  the  places  on  the  leaves  on  which  it  falls.  This  result  is  as 
bad  for  the  plant  as  it  would  be  to  have  the  leaves  eaten,  for  the  object 
of  spraying  is  to  prevent  injury  or  loss  of  leaf  surface.  Because  of  its 
solubility  in  water,  therefore,  arsenic,  as  such,  is  not  employed  as  a  spray, 
but  combinations  of  it  with  other  materials,  not,  or  only  very  slightly 
soluble,  have  been  selected  for  use  instead.  This  produces  another  diffi- 
culty. A  combination  with  lead  can  be  obtained  for  example,  which  is 
almost  absolutely  insoluble  in  water  and  therefore  entirely  safe  for  use 
as  a  spray.  But  in  this  material  only  about  one-quarter  of  it  is  arsenic, 
so  that  an  insect,  speaking  in  a  general  way,  would  be  obliged  to  eat 
about  four  times  as  much  before  being  poisoned,  as  would  be  the  case  had 
the  material  been  arsenic  instead.  By  the  use  of  more  or  less  insoluble 
combinations  of  arsenic  with  other  substances,  then,  reduced  injury  to 
the  foliage  can  largely  be  secured,  but  a  larger  leaf  surface  is  consumed  by 
the  insect  before  the  poisonous  dose  is  obtained.  This  is  a  small  matter, 
however,  as  compared  with  the  protection  of  all  the  foliage  on  a  tree  from 
injury  by  the  spray. 

Another  difficulty  in  the  use  of  sprays  is  the  weight  of  the  poison 
mixed  in  and  carried  by  the  water.  It  has  just  been  pointed  out  that 


INSECTICIDES  IN  GENERAL:  STOMACH  POISONS  45 

the  poison  must  not  dissolve,  or  burning  of  the  foliage  will  result.  The 
poison,  instead,  must  be  suspended  in  the  water,  which  acts  merely  as  a 
carrier  from  the  pump  to  the  plant  over  which  it  distributes  the  poison. 
This  distribution  should  be  as  uniform  as  possible  in  order  that  all  parts  of 
the  plant  may  be  equally  well  protected  and  covered.  If  the  poison  be 
heavy,  settling  quickly  to  the  bottom  of  the  pump,  uneven  distribution 
will  result,  some  parts  of  the  plant  receiving  too  much  of  the  poison  while 
others  will  get  but  little.  The  best  stomach  poison  from  this  standpoint 
therefore,  is  one  which  is  so  light  that  after  mixing  it  with  water  it  will 
take  a  long  time  to  settle  to  the  bottom. 

The  chief  stomach  poisons  now  in  use  in  the  United  States  are  Paris 
green,  Arsenate  of  lead,  Arsenate  of  lime,  Hellebore,  and  Sodium  fluorid, 
the  last  two  having  only  a  limited  application.  Standard  formulas  for 
these  are  given  below.  Variations  from  them  will  be  found  in  connection 
with  the  special  cases  where  change  from  the  standard  is  desirable. 

Paris  Green. — This  was  probably  the  first  stomach  poison  used  against 
insects,  having  been  first  employed  about  1868  for  the  treatment  of  the 
Colorado  potato  beetle.  Chemically,  it  is  a  combination  of  copper, 
arsenic  and  acetic  acid,  containing  when  pure,  nearly  60  per  cent  of  arsenic, 
which  is  high  as  compared  with  the  other  arsenicals  in  use,  and  this  gives 
the  substance  its  chief  value. 

Paris  green  has  three  serious  disadvantages.  One  of  these  is  that 
some  of  the  arsenic  will  dissolve  in  the  water  it  is  mixed  with,  causing 
injury  to  the  foliage.  This  can  in  part  be  avoided  by  the  addition  of  lime, 
which  combines  with  any  of  the  arsenic  that  separates  from  its  combina- 
tion with  the  copper  and  acetic  acid  and  would  cause  burning,  converting 
it  into  arsenite  of  lime  which  is  only  slightly  soluble  under  such  circum- 
stances. Sometimes  though,  a  slight  burning  takes  place,  even  under 
these  conditions.  By  Federal  law,  not  over  3  per  cent  should  be  soluble. 

A  second  disadvantage  is  that  Paris  green  is  a  heavy  substance, 
settling  quickly  through  the  water  to  the  bottom  of  the  pump,  which 
results  in  an  uneven  distribution  over  the  plant. 

The  third  disadvantage  is  that  it  does  not  adhere  well  to  foliage,  being 
easily  washed  off  by  rains.  This  means  that  more  frequent  sprayings  are 
necessary  for  the  protection  of  the  plants  than  would  otherwise  be  the 
case,  involving  greater  cost  for  material  and  labor. 

A  standard  formula  for  Paris  green  is: 

PER  BARREL  PER  GALLON 

Paris  green , Y%    Ib.  }••£  teaspoonful  (level) 

Quick  lime 1  Ib.  1  teaspoonful  (level) 

Water 50  gal.  1  gal. 

Use  fresh  stone  lime,  slaking  this  in  some  of  the  water:  work  up  the  Paris 
green  to  a  paste  in  a  little  of  the  water:  add  the  lime  slaked,  to  the  rest  of 
the  water,  then  stir  in  the  Paris  green  paste.  It  is  not  advisable  to  mix 


46  APPLIED  ENTOMOLOGY 

this  long  before  it  is  to  be  used,  nor  to  mix  more  than  will  be  used  the 
same  day. 

Although  the  addition  of  lime  to  the  Paris  green  reduces  the  danger 
of  injuring  foliage,  some  plants  even  then,  are  liable  to  be  burned  some- 
what. Accordingly,  the  amount  of  the  poison  to  use  per  barrel  will  vary. 
Thus,  for  potatoes  the  Paris  green  can  usually  be  increased  to  %  Ib.  per 
barrel,  while  for  the  peach  it  is  not  safe  to  use  more  than  ^  Ib.  It 
should  not  be  used  on  evergreens. 

Applied  as  a  dust  it  is  usually  thoroughly  mixed  with  flour,  plaster  or 
air-slaked  lime,  in  about  the  proportion  of  1  part  of  the  Paris  green  to 
from  6  to  10  parts  of  the  other,  by  weight. 

Paris  green  is  unsafe  to  apply  on  stone  fruit  foliage,  and  because  of  the 
danger  of  burning  in  general,  it  is  now  less  used  than  was  once  the  case, 
arsenate  of  lead  having  largely  replaced  it  as  a  spray. 

Arsenate  of  Lead. — The  value  of  this  material  as  a  spray  against  insects 
was  discovered  about  1892  in  the  course  of  the  work  conducted  by  the 
State  of  Massachusetts  on  the  control  of  the  gypsy  moth,  and  it  has  now 
been  generally  adopted  as  being,  under  ordinary  conditions,  the  best 
stomach  poison  to  use.  Two  forms  of  it  are  available:  the  basic  or  neu- 
tral (ortho)  arsenate,  Pb3(AsO4)2  and  the  acid  arsenate,  PbHAsO4.  In 
pure  condition  the  former  is  about  25  per  cent  arsenic  oxid  and  the  latter 
about  33  per  cent.  The  latter  is  the  form  in  most  general  use,  but  on  the 
Pacific  Coast,  because  of  local  conditions,  the  former  appears  to  be  re- 
garded with  more  favor. 

Arsenate  of  lead  may  be  obtained  both  as  a  paste  and  as  a  powder. 
By  law  the  paste  must  not  be  more  than  half  water,  but  with  about  this 
amount  present  the  percentage  of  arsenic  oxid  in  it  is  reduced  to  from 
12  or  13  to  19  or  20  per  cent.  In  the  powder,  water  being  practically 
absent,  about  32  to  33  per  cent  is  arsenic  oxid.  As  the  average  in  the 
paste  is  usually  16  per  cent  and  the  price  of  the  powder  is  about  double 
that  of  the  paste,  there  is  little  choice  between  the  two  so  far  as  the  arsenic 
is  concerned.  The  Federal  law  requires  that  in  the  paste  no  more  than 
0.75  per  cent  of  the  arsenic  oxid  shall  be  soluble  in  water. 

Either  form  of  arsenate  of  lead  shows  well  on  the  foliage,  which  is 
useful,  enabling  the  sprayer  to  see  parts  he  has  missed  in  spraying,  and 
to  " touch  up"  those  places.  It  is  also  very  light,  settling  slowly  in  the 
pump.  Under  most  conditions  arsenate  of  lead  does  not  burn  the  leaves, 
being  in  fact,  the  safest  of  the  stomach  poisons  in  this  regard,  and  it 
adheres  to  the  leaves  longer  than  the  others  (stomach  poisons).  On 
the  other  hand,  it  acts  slowly  on  insects  because  of  its  rather  low  arsenic 
content 

As  a  pound  of  the  paste  is  approximately  one-half  water,  it  is  necessary 
in  spraying  a  given  area  to  use  twice  as  much  (by  weight)  as  of  the 
powder,  in  order  to  supply  equal  amounts  of  the  poison. 


INSECTICIDES  IN  GENERAL:  STOMACH  POISONS  47 

A  standard  formula  for  arsenate  of  lead  is: 

PER  BARREL  PER  GALLON 

Arsenate  of  lead  paste 3      Ib.       3      teaspoonfuls  (level) 

Water 50      gal.      1      gal. 

Arsenate  of  lead  powder 1%  Ib.        9K  teaspoonfuls  (level) 

Water 50  gal.         1        gal. 

In  mixing  the  paste  it  is  well  to  add  some  water  and  stir  thoroughly 
before  adding  the  rest  of  the  water,  in  order  to  get  a  more  uniform  mix- 
ture. If  it  is  allowed  to  dry  it  will  not  work  up  well  thereafter  by  adding 
water,  and  it  is  also  injured  by  freezing. 

Arsenate  of  Lime. — This  substance  has  come  into  use  since  about 
1914,  because  of  the  rapidly  increasing  cost  of  arsenate  of  lead.  It 
is  Ca3(AsO4)2  and  may  be  obtained,  like  arsenate  of  lead,  either  as  a  paste 
or  a  powder.  The  former  contains  about  18  per  cent  of  arsenic  oxid, 
and  the  latter  about  44  per  cent,  thus  being  slightly  higher  in  paste  form, 
and  considerably  higher  in  powder  form,  than  arsenate  of  lead.  As  the 
costs  of  the  two  forms  differ  correspondingly,  there  is  little  choice  between 
them  from  this  standpoint,  but  convenience  and  other  factors  give  a  slight 
preference  to  the  powder.  Being  stronger  than  arsenate  of  lead,  less 
needs  to  be  used  in  order  to  supply  an  equal  amount  of  poison  to  a  given 
area. 

Arsenate  of  lime  is  not  safe  for  use  on  foliage,  and  particularly  that  of 
stone  fruits,  unless  an  excess  of  lime  is  present.  Accordingly,  as  was  the 
case  with  Paris  green,  lime  must  be  added  to  the  mixture. 

A  standard  formula  for  arsenate  of  lime  is: 

PER  BARREL          PER  GALLON 

Arsenate  of  lime  paste. 2      Ib.  1%  teaspoonfuls 

Quick  lime 2  to    3      Ib.  2      teaspoonfuls 

Water 50      gal.  1      gal. 

Arsenate  of  lime  powder %      Ib.        4%  teaspoonfuls 

Quick  lime 1      Ib.        9      teaspoonfuls 

Water 50      gal.      1      gal. 

The  quick  lime,  which  should  be  fresh  stone  lime,  is  slaked  in  some  of 
the  water,  then  added  to  the  rest,  and  the  arsenate  of  lime  thoroughly 
stirred  in. 

While  this  material  is  cheaper  than  arsenate  of  lead  and  perhaps 
kills  a  little  more  quickly,  it  has  not  been  in  use  long  enough  to  be  certain 
just  what  results  may  be  expected  in  all  cases.  At  least  it  may  at  the 
present  time  be  termed  a  very  promising  insecticide. 

Poison  Baits. — These  are  included  here,  as,  in  most  cases  at  least, 
they  contain  an  arsenical  poison.  They  are  used  mainly  for  the  control 
of  cutworms  and  grasshoppers.  There  are  several  formulas  proposed, 


48  APPLIED  ENTOMOLOGY 

but  those  consisting  of  bran  or  horse  manure,  poisoned  with  arsenic  or 
Paris  green,  and  made  attractive  to  the  insect  by  adding  strong-smelling 
molasses  (syrup)  and  the  juice  of  citrus  fruits,  have  in  general  been  the 
most  successful.  Detailed  consideration  of  them  will  be  given  in  con- 
nection with  the  insects  for  which  they  are  used. 

Hellebore. — This  is  the  powdered  roots  of  the  plants  Veratrum 
album  and  Veratrum  viridis.  It  is  a  mild  stomach  poison  and  can 
therefore  be  used  with  safety  to  man,  on  plants  soon  to  be  gathered  for 
food,  as  it  loses  its  strength  quite  quickly  on  exposure  to  the  air.  It  is 
sometimes  difficult  to  obtain  fresh. 

It  may  be  dusted  over  the  plants,  sticking  on  best  if  applied  while  dew 
is  on  them,  or  it  may  be  mixed  with  from  one  to  three  times  its  bulk  of 
flour  or  plaster,  for  this  purpose.  It  may  also  be  used  as  a  spray  by 
steeping  an  ounce  in  a  quart  of  water  and  then  adding  another  quart  of 
water.  At  the  rate  of  half  a  pound  in  10  gal.  of  water  it  is  effective  against 
house-fly  maggots  in  manure  piles.  It  is  too  expensive  to  use  except  on  a 
small  scale. 

Commercial  Sodium  Fluorid. — This  substance  has  recently  been  found 
to  be  effective  for  some  insects,  acting  apparently  both  as  a  stomach 
poison  and  as  a  contact  insecticide.  It  is  applied  as  a  dust,  either 
pure  or  mixed  in  about  equal  parts,  with  flour  or  plaster.  Details  are 
given  in  connection  with  the  insects  against  which  it  is  used. 


CHAPTER  VIII 
CONTACT  INSECTICIDES 

For  insects  which  do  not  feed  upon  solid  food,  stomach  poisons  are 
useless,  anpl  sprays  which  come  in  contact  with,  and  kill  them  in  one  or 
another  of  the  ways  already  indicated,  must  be  used.  This  is  unfortunate 
for  it  means  the  most  thorough  kind  of  work  if  all  the  insects  are  to  be 
reached  by  the  spray.  It  is  among  such  insects  too,  that  the  greatest 
difficulties  in  accomplishing  this,  occur.  Some,  though  large  enough  to  be 
almost  certainly  reached  by  the  spray  have  a  particularly  thick  outer 
shell:  others  are  exceedingly  small  and  thus  can  find  protection  under 
buds,  in  crevices  of  the  bark  and  in  other  places  where  the  spray  may  not 
reach  them:  still  others  form  protective  coverings  (scales)  over  them- 
selves, which  fit  tightly  to  the  objects  they  may  be  on,  so  that  a  successful 
spray  must  be  very  strong  and  penetrating:  and  finally,  many  of  the 
smallest  and  also  of  the  scale-protected  insects  have  marvelous  powers  of 
increase,  so  that  if.  even  a  single  individual  escapes  treatment,  a  few 
days  or  a  week  or  two  will  find  the  plant  again  swarming  with  these 
insects. 

Every  insect  therefore,  which  can  be  killed  by  a  stomach  poison  is 
best  controlled  by  such  materials.  For  the  others,  oils,  soaps,  nicotine, 
sulfur  compounds  and  a  few  other  substances  of  minor  importance  serve 
as  contact  insecticides. 

Considering  the  oils  first,  there  are  several  which  are  of  use.  Among 
mineral  oils,  crude  petroleum  and  kerosene  are  destructive  to  insect  life 
but  so  dangerous  to  plants  when  of  full  strength,  that  some  method  of 
dilution  becomes  necessary. 

Kerosene  Emulsion :  standard  formula : 

Common  laundry  soap %    Ib. 

Soft  water 1      gal. 

Kerosene 2      gal. 

Dissolve  the  soap  in  the  water  (best  by  shaving  it  into  hot  water) : 
then  add  the  kerosene  and  with  a  small  hand  spray  pump  having  a  fine 
nozzle,  draw  the  mixture  into  the  pump  and  out  through  the  nozzle  back 
into  the  dish  from  which  it  was  drawn.  In  a  few  minutes  it  should 
become  creamy  and  then  begin  to  thicken.  When  it  has  become  so 
thick  as  to  go  hard  through  the  pump,  this  process  has  been  completed, 
4  49 


50  APPLIED  ENTOMOLOGY 

giving  a  Stock  Solution  in  which  the  oil,  broken  up  into  very  tiny  droplets, 
will  not  run  together  again  and  the  water  can  dilute  the  mixture.  For  use 
against  soft-bodied  insects,  1  part  of  the  Stock  Solution  is  mixed  with 
about  9  parts  of  water  to  spray,  while  for  tougher  insects,  1  part  is  diluted 
with  4  or  5  parts  of  water,  though  this  strength  may  sometimes  injure 
the  plants  somewhat.  The  Stock  Solution,  if  well  prepared,  should  keep 
before  breaking  down  (shown  by  a  film  of  oil  appearing  on  the  surface) 
for  at  least  a  month  or  two.  If  the  materials  fail  to  thicken  in  the  pump 
it  is  probably  because  the  water  is  "hard  water."  In  that  case  add  a 
little  borax  or  soda  to  soften  it. 

Crude  Petroleum  can  be  used  in  place  of  kerosene  in  preparing  this 
emulsion,  provided  the  right  grade  can  be  obtained,  but  this  is  often 
difficult,  and  so  is  not  frequently  done. 

Miscible  Oils. — These  are  stronger  than  kerosene  emulsion.  They 
contain  mineral  oils,  a  small  amount  of  vegetable  oil,  naphthaline  in 
some  cases,  some  alkali,  and  water.  Properly  made  they  dilute  readily 
with  water. 

A  number  of  brands  of  miscible  oils  are  on  the  market,  prepared 
mainly  as  sprays  for  the  control  of  scale  insects.  For  winter  use  against 
scales  they  are  generally  diluted  at  the  rate  of  1  part  of  the  oil  to  12 
to  14  parts  of  water.  When  used  in  summer  against  plant  lice  the  dilu- 
tion should  be  about  1  part  to  35  to  40  parts  of  water. 

The  material  should  not  be  used  if  free  oil  stands  on  it,  as  this  shows 
that  it  has  broken  down  and  is  not  safe  on  the  plants.  If  sprayed  on  trees 
in  freezing  weather  it  may  gather  and  freeze  in  cracks  of  the  trees,  in- 
juring them.  It  is  easy  to  handle  and  spreads  readily  from  where  it 
strikes,  covering  more  than  would  otherwise  be  the  case,  but  it  has  been 
claimed,  with  considerable  evidence  to  support  it,  that  repeated  treat- 
ments with  miscible  oils  cause  a  cumulative  injurious  effect  on  trees. 

Among  soaps,  common  laundry  soap  and  whale-oil  (generally  fish-oil 
now)  soap  are  the  usual  materials  used  as  insecticides. 

Whale-oil  Soap. — This  is  a  soap  made  by  combining  fish  oil  with  an 
alkali,  preferably  potash.  It  is  usually  diluted  at  the  rate  of  1  Ib.  to  5 
or  6  gal.  of  water  to  apply  against  plant  lice  and  similar  soft-bodied 
insects  in  summer,  but  is  also  a  fair  winter  application  for  scale  insects, 
at  the  rate  of  2  Ib.  per  gallon  of  water,  though  more  costly  than  other, 
equally  good  materials. 

Common  Soap. — This  is  a  fairly  good  material  at  the  rate  of  1  Ib.  in 
3  to  5  gal.  of  water  for  summer  use  against  plant  lice  and  other  soft- 
bodied  insects  but  is  not  as  effective  as  whale-oil  soap  and  is  mentioned 
only  because  the  latter  cannot  always  be  obtained. 

Nicotine. — This  is  an  alkaloid  which  occurs  in  tobacco.  It  can  be 
obtained  by  soaking  tobacco  stems  in  warm  water  till  a  dark  brown  liquid 
containing  nicotine  is  obtained,  and  this  is  of  some  value  as  an  insecticide. 


CONTACT  INSECTICIDES  51 

Tobacco  dust  is  also  used  around  plants  as  an  insect  repellent  as  well  as  a 
fertilizer. 

Nicotine  obtained  as  above  indicated,  is  variable  in  its  strength  and 
the  amount  it  should  be  diluted  for  use  is  uncertain.  It  is  also  quite 
volatile  and  this  is  a  disadvantage  when  it  is  used  as  a  spray. '  Com- 
mercial nicotine  compounds  "on  the  market  avoid  these  difficulties  by 
supplying  a  material  containing  a  fixed  percentage  of  nicotine  combined 
with  sulfuric  acid,  known  as  nicotine  sulfate  40  per  cent.  This  can  be 
diluted  to  the  proper  strength  with  accuracy,  and  does  not  pass  off  into 
the  air  rapidly.  Nicotine  uncombined,  of  the  same  strength,  can  also 
be  obtained?  but  should  be  used  for  fumigation  and  not  as  a  spray. 

Nicotine  sulfate  is  an  excellent  material  to  use  for  plant  lice  and  other 
delicate  insects.  It  is  generally  diluted  at  the  rate  of  1  gal.  to  800  or 
1,000  gal.  of  water,  and  in  some  cases  a  greater  dilution  even,  than  this  is 
possible.  Sometimes  dilution  at  the  rate  of  1  to  500  is  desirable. 

Standard  formula  for  nicotine  sulfate  40  per  cent,  1  part  to  800  of 
water : 

PER  BARREL  PER  GALLON 

Nicotine  sulfate,  40  per  cent 3-2      P'nt  1H  teaspoonfuls 

Soap 2  to    3      Ib.  1      oz. 

Water 50      gal.  1      gal. 

Three-eighths  of  a  pint  in  50  gal.  of  water,  or  1  teaspoonful  in  a 
gallon,  gives  nearly  a  dilution  of  1  to  1,000.  The  addition  of  soap 
causes  the  material  to  spread  more  and  adhere  better. 

Among  the  various  sulfur  compounds,  those  with  lime  have  thus  far 
been  found  to  be  the  most  successful. 

Lime -sulfur  Wash. — This  is  prepared  by  boiling  lime  and  sulfur 
together  in  water.  Several  substances  are  produced  by  this  boiling, 
but  apparently  its  insecticidal  value  is  determined  by  the  quantity  of 
calcium  polysulfids  (CaS4  and  CaSs)  and  possibly  the  calcium  thiosulfate 
(CaS2O3)  which  are  formed  in  the  mixture.  The  wash  can  be  made  at 
home  but  it  is  generally  easier  to  buy  it  in  concentrated  form  and  dilute 
as  needed.  It  will  vary  in  specific  gravity  in  different  cases,  and  its 
reading  must  be  taken  (a  Beaume  hydrometer  is  generally  used  for  this 
purpose)  in  order  to  dilute  it  properly.  The  range  in  readings  of  differ- 
ent lots  may  vary  as  much  as  5°  or  more,  but  is  usually  about  33°Be*. 
Thus,  a  sample  of  this  density  should  have  6J-4  gal.  mixed  with  43%  gal. 
of  water  to  be  of  the  proper  strength  for  use  as  a  winter  spray  for  the 
San  Jose"  Scale,  when  this  insect  is  dormant;  while  if  its  density  is  30°Be., 
7  gal.  should  be  mixed  with  43  gal.  of  water.  Tables  of  density,  Beaume* 
readings,  and  the  amount  of  concentrate  to  add  to  water  to  make  a  total 
of  50  gal.  of  spray,  both  for  winter  use  and  as  a  foliage  spray  in  summer, 
can  be  obtained  by  applying  to  any  state  experiment  station  or  to  the 
U.'S.  Bureau  of  Entomology. 


52  APPLIED  ENTOMOLOGY 

The  Lime-sulfur  wash  is  used  both  as  a  strong  spray  against  insects 
during  their  dormant  season,  and  as  a  weaker  one  for  general  purposes 
during  the  summer.  In  the  latter  case,  besides  being  a  contact  insecti- 
cide, it  has  a  little  value  as  a  stomach  poison.  It  cannot  safely  be  used 
on  stone  fruits  or  potatoes,  however. 

This  material  must  be  kept  in  air-tight  containers  as  it  decomposes 
on  standing  when  exposed  to  the  air.  A  film  of  some  vegetable  oil  over  it, 
for  partly  filled  containers,  will  give  this  protection.  It  should  not  be 
allowed  to  freeze. 

For  stone  fruits  where  a  summer  treatment  seems  necessary,  self- 
boiled  lime-sulfur  may  be  used.  This  is  prepared  by  slaking  8  Ib.  of 
fresh  stone  lime  in  a  barrel,  in  enough  water  to  nearly  cover  it.  Eight 
pounds  of  fine  sulfur  should  be  gradually  added  to  this,  as  soon  as  the 
lime  begins  to  slake,  running  the  sulfur  in  through  a  sieve  to  break  up  any 
lumps.  This  mixture  should  be  constantly  stirred  and  more  water 
added  to  form  first  a  thick  paste,  then  gradually  a  thin  one.  The  heat 
produced  by  the  lime  in  slaking  will  cause  the  mixture  to  boil  for  several 
minutes.  When  slaking  is  at  an  end,  cool  the  mixture  rapidly  by  adding 
considerable  water,  then  strain  into  the  pump  to  remove  lumps  of  lime, 
but  working  any  lumps  of  sulfur  through  the  strainer;  then  dilute  with 
water  to  a  total  of  50  gal. 

Dry  Sulfur  Compounds. — These  substances  have  recently  appeared 
in  competition  with  the  lime-sulfur  wash,  the  advantages  claimed  for 
them  being  ease  of  handling,  reduction  of  shipping  charges,  no  deteriora- 
tion on  standing,  and  equal  efficiency  at  lower  cost. 

These  substances  are  sulfid  combinations  with  either  potassium, 
sodium,  barium  or  calcium.  The  amount  of  sulfur  present  varies  greatly 
in  different  brands.  They  do  not  contain  as  much  of  the  polysulfids 
which  appear  to  be  the  actual  insecticides  of  the  lime-sulfur  wash  as  the 
liquid  wash,  and  even  the  amount  of  sulfur  present  in  them,  after  the 
addition  of  water  according  to  directions,  is  less  than  in  an  equal  quantity 
of  the  wash,  so  that  basing  efficiency  on  the  amount  of  sulfur,  regardless 
of  its  form,  the  amounts  of  these  dry  materials  would  have  to  be  greatly 
increased  to  equal  that  of  the  wash,  and  would  therefore  seriously  increase 
their  cost.  At  the  present  time  their  value  cannot  be  considered  as 
having  been  finally  settled  though  in  many  cases  field  tests  of  them  have 
given  good  results.  Continued  studies  and  tests  of  these  materials  are 
needed  to  determine  their  real  value. 

Sulfur. — This  substance  in  the  form  of  a  very  fine  powder,  can  be 
dusted  over  plants  for  the  destruction  of  red  spiders  and  other  mites, 
or  it  may  be  made  into  a  paste  with  soapy  water,  using  10  Ib.  of  sulfur 
and  2  Ib.  of  soap  in  50  gal.  of  water,  and  applied  as  a  spray  Its  use  is 
rather  limited  and  its  actual  value  somewhat  questionable  in  many  cases. 


CONTACT  INSECTICIDES  53 

Pyrethrum,  Insect  Powder  or  Buhach. — This  is  made  by  grinding 
up  the  blossoms  of  certain  plants,  which  contain  an  essential  (and  volatile) 
oil  effective  against  insects  but  not  injurious  to  man.  Its  use  is  mainly 
limited  to  small  areas,  and  best,  those  which  can  be  tightly  closed. 

Various  other  materials  will  be  considered  in  connection  with  the 
particular  insects,  for  the  control  of  which  they  are  used. 


CHAPTER  IX 
INSECTICIDES  AND  FUNGICIDES :  FUMIGATION 

COMBINATIONS  OF  SPRAY  MATERIALS 

The  greater  part  of  the  cost  of  spraying  comes  from  the  time  and 
wages  of  the  workers,  the  materials  used  being  rather  inexpensive  in 
comparison..  Wherever  it  is  possible  therefore,  to  make  two  or  three 
applications  at  once  by  using  combined  sprays,  the  cost  is  much  reduced. 

Frequently  there  are  cases  where  the  application  of  a  stomach  poison 
for  chewing  insects  and  of  a  contact  insecticide  for  sucking  forms,  can 
be  made  at  about  the  same  time.  Treatment  for  fungous  diseases  may 
also  be  desirable,  and  a  satisfactory  mixed  spray  for  all  three  purposes 
can  often  be  given.  Certain  precautions  'must  be  taken  in  mixing  sprays, 
however,  as  in  some  instances  the  materials  of  two  or  more  sprays,  when 
combined,  will  undergo  changes,  producing  substances  injurious  to  the 
plant  or  affecting  the  value  of  the  spray  for  the  purpose  for  which  it  was 
intended. 

No  spray  material  containing  soap  should  be  combined  with  one  con- 
taining lime,  as  when  these  materials  are  brought  together,  a  calcareous 
and  insoluble  soap  is  formed.  Thus,  when  nicotine  sulfate  is  used  with 
lime-sulfur  or  Bordeaux  mixture,  the  soap  usually  added  to  the  former 
must  never  be  put  in.  Arsenate  of  lead  and  compounds  containing 
sodium  or  potassium  sulfid,  when  mixed,  produce  sodium  or  potassium 
arsenate  which  is  very  soluble  and  will  injure  foliage,  so  this  combination 
should  also  be  avoided. 

Bordeaux  mixture,  a  fungicide,  combines  well  with  most  of  the  insec- 
ticides except  those  containing  soap,  but  as  it  contains  lime,  an  insec- 
ticide with  soap  is  not  safe  for  this  combination.  In  most  cases  the 
Bordeaux  mixture  ready  for  spraying  can  be  regarded  as  an  equivalent 
amount  of  water,  to  which  to  add  the  insecticide.  For  example,  in 
combining  Bordeaux  and  arsenate  of  lead,  simply  add  3  Ib.  of  the  paste 
to  50  gal.  of  the  Bordeaux. 

Bordeaux  mixture  will  safely  combine  with  any  of  the  arsenical 
poisons  given  in  this  book,  and  also  with  nicotine  sulfate  if  the  soap 
be  omitted.  Lime-sulfur  at  summer  strength  may  be  used  with  arsenate 
of  lead  or  nicotine  sulfate,  leaving  out  the  soap,  though  in  the  former 
case  a  decomposition  is  liable  to  take  place  which  reduces  the  value 
of  the  material.  Lime-sulfur  at  winter  strength  when  added  to  the 

54 


INSECTICIDES  AND  FUNGICIDES:  FUMIGATION  55 

arsenate  of  lead  brings  about  a  decomposition,  as  a  result  of  which  con- 
siderable soluble  arsenic  is  formed,  and  the  efficiency  of  the  lime-sulfur 
is  also  reduced  about  one-third.  This  may  be  avoided,  however,  by 
slaking  5  Ib.  of  quick  lime  and  adding  this  to  the  lime-sulfur  before  putting 
in  the  arsenate  of  lead. 

Lead  arsenate  can  be  combined  with  nicotine  sulfate,  and  in  some  cases 
at  least,  with  kerosene  emulsion.  With  soap,  acid  lead  arsenate  decom- 
poses to  some  extent  forming  a  soluble  arsenate  which  is  dangerous  on 
foliage.  Small  amounts  of  soap  added  as  a  "  sticker,"  however,  are  often 
advantageous  even  in  spite  of  this  decomposition  and  are  frequently 
recommended,  the  gain  by  the  addition  of  the  soap  being  greater  than 
a  small  injury  by  burning. 

FUMIGATION 

In  theory,  fumigation  is  the  best  method  for  the  control  of  insects. 
A  gas  will  reach  every  portion  of  a  room  or  a  plant,  penetrating  where  no 
spray  can  reach,  so  that  insects  no  matter  how  well  concealed  in  crevices, 
under  bark  or  in  other  locations,  will  be  reached.  Still,  practical  diffi- 
culties in  the  use  of  poisonous  gases  are  numerous  and  result  in  a  restricted 
use  of  this  method  of  treatment. 

The  gases  used  for  the  destruction  of  insects  act  either  as  actual 
poisons  which  enter  the  body  through  the  tracheal  system  and  directly 
attack  the  tissues,  or  combine  with  the  oxygen  of  the  air  and  thus  remove 
it  from  availability  by  the  insect,  which  suffocates  in  consequence.  In 
either  case,  successful  fumigation  depends  upon  the  liberation  of  a  suf- 
ficient quantity  of  the  gas  or  vapor  to  make  it  strong  enough  to  kill  the 
insect. 

This  at  once  eliminates  trees,  bushes  and  crops  growing  out  of  doors 
from  consideration,  unless  they  or  their  products  are  so  valuable  as  to 
make  the  use  of  gas-tight  tents  to  cover  them  during  treatment  worth 
the  expense,  which  is  considerable.  Accordingly,  fumigation  is  generally 
made  use  of  only  with  citrus  trees,  and  in  houses,  greenhouses  or  other 
places  capable  of  being  tightly  closed.  Under  the  conditions  mentioned, 
however,  it  is  an  excellent  method  for  insect  control,  though  where  plants 
are  to  be  fumigated,  it  is  usually  done  at  night  as  the  gases  or  vapors  are 
less  liable  to  cause  injury  then. 

The  fumigants  most  often  used  are  carbon  disulfid,  nicotine,  sulfur 
and  hydrocyanic  acid  gas. 

Carbon  Disulfid  (CS2). — This  is  obtained  in  liquid  form  but  becomes 
a  gas  on  exposure  to  the  air.  Impure  grades  are  as  good  for  fumigation 
as  the  purified  article.  The  number  of  cubic  feet  in  the  space  to  be  fumi- 
gated is  calculated,  and  in  general  from  10  to  20  Ib.  of  the  disulfid 
are  used  for  each  1,000  cu.  ft.,  though  if  the  place  is  very  tight,  less  than 
this  will  be  needed.  As  the  gas  is  considerably  heavier  than  air,  the  usual 


56  APPLIED  ENTOMOLOGY 

practice  is  to  put  the  liquid  in  rather  flat  dishes  close  to  the  top  of  the 
place  to  be  fumigated,  as  the  gas  will  develop  more  rapidly  in  such  dishes 
and  work  downward  from  its  source.  All  openings  into  this  place  must 
then  be  tightly  closed  at  once  and  everything  be  left  undisturbed  for  from 
24  to  48  hr.  Ventilate  well  from  outside  before  entering. 

The  chief  disadvantage  in  the  use  of  this  gas  is  that  it  is  quite  inflam- 
mable and  cannot  be  used  near  where  there  is  a  fire  or  highly  heated  pipes 
of  any  kind.  In  such  quantities  as  the  operator  is  likely  to  inhale  while 
using  it,  a  headache  is  generally  the  most  serious  result,  though  persons 
with  heart  trouble  of  any  kind  should  not  work  with  it  as  it  has  some  effect 
on  that  organ. 

Carbon  disulfid  is  used  chiefly  against  clothes  moths,  carpet  beetles, 
stored  grain  pests,  pea,  bean,  and  other  seed  pests,  ants,  and  borers  in 
trees.  It  cannot  safely  be  used  in  greenhouses  or  with  plants.  Details 
of  its  uses  in  different  cases  will  be  given  in  connection  with  the  different 
insects  concerned. 

Nicotine. — Nicotine  as  a  vapor  may  be  obtained  by  evaporating  the 
decoction  of  it  mentioned  in  the  last  chapter,  in  a  dish  over  a  lamp,  but 
the  uncertainty  as  to  its  strength  makes  treatment  in  this  way  liable  to 
prove  unsatisfactory. 

Nicotine  40  per  cent,  both  in  liquid  form  and  as  paper  rolls  saturated 
with  it,  are  on  the  market  and  supply  a  material  of  known  strength  with 
which  to  work.  It  is  of  value  as  a  treatment  for  plant  lice  and  other 
delicate  insects.  A  fluid  ounce  added  to  a  little  water,  and  this  evapo- 
rated by  heat  will  be  sufficient  for  about  l,000cu.  ft.  of  space,  provided  the 
place  is  quite  tight;  or  four  or  five  sheets  of  the  paper  are  usually  enough. 
Upon  lighting,  the  paper  smolders,  giving  off  the  nicotine  vapor.  The 
length  of  time  necessary  for  nicotine  treatment  varies  with  different 
insects,  but  is  generally  begun  in  the  evening,  continued  all  night,  and 
the  place  opened  and  aired  the  next  morning. 

Sulfur. — The  value  of  sulfur  as  a  fumigant  is  probably  due  both  to  its 
combination  on  burning  with  the  oxygen  of  the  air,  eliminating  this  and 
suffocating  the  insect,  and  to  the  formation  in  this  way  of  a  poisonous  gas. 
It  is  prepared  by  burning  powdered  sulfur  in  the  place  to  be  fumigated, 
and  is  used  for  household  pests  and  also  in  greenhouses  between  crops. 
It  cannot  be  safely  used  with  living  plants.  From  1  to  2  Ib.  of  sulfur  per 
1,000  cu.  ft.  of  space  is  the  usual  quantity  used.  Polished  metal  surfaces 
in  the  place  to  be  fumigated  will  become  tarnished  by  the  gas,  and  these 
should  be  removed,  as  well  as  colored  goods  which  are  bleached  by  it. 
Metal  can  be  protected  by  covering  it  with  vaseline. 

The  general  practice  is  to  place  a  large  iron  kettle  on  bricks  to  keep 
it  off  the  floor,  which  in  that  place  should  be  covered  for  a  distance  of 
several  feet  with  something  which  will  not  be  injured  or  burned  if  the 
sulfur  spatters  over.  In  the  kettle  place  the  sulfur  and  add  to  it  a  little 


INSECTICIDES  AND  FUNGICIDES:  FUMIGATION  57 

denatured  alcohol  to  insure  burning :  then  light  the  sulfur  and  keep  the 
place  tightly  closed  for  24  to  48  hr.;  then  air  thoroughly. 

Hydrocyanic -acid  Gas  (HCN). — This  is  one  of  the  most  powerful  and 
dangerous  gases  known,  and  persons  having  had  no  training  in  its  use  are 
advised  not  to  try  it.  It  is  produced  by  the  addition  of  sodium  or  potas- 
sium cyanid  to  sulf uric  acid  which  has  been  diluted  with  water.  Formerly, 
potassium  cyanid  was  used  almost  entirely  but  now  the  sodium  cyanid  has 
taken  its  place.  Care  should  be  taken  that  the  cyanid  is  of  good  quality 
and  (at  least  for  use  with  plants)  contains  no  chlorine.  If  potassium 
cyanid  is  used  it  should  contain  38  per  cent  of  cyanogen :  if  sodium  cyanid, 
51  to  52  per  cent.  The  sulf  uric  acid  should  have  a  specific  gravity  of  1.83 
and  be  free  of  any  nitric  acid. 

Hydrocyanic-acid  gas  can  be  used  to  advantage  in  the  following  ways: 

(a)  For  household  and  storehouse  pests  and  for  fumigating  bales  of 
imported  cotton. 

(6)  For  greenhouse  insects. 

(c)  For  insects  on  dormant  nursery  stock. 

(d)  For  insects  on  citrus  trees. 

For  the  first  class,  an  ounce  of  sodium  cyanid  for  every  100  cu.  ft.  of 
space  is  used,  and  at  least  2  hr.  of  fumigation  is  necessary. 

For  greenhouse  insects  the  dose  is  J^  to  %  oz.  of  sodium  cyanid  for 
every  1,000  cu.  ft.,  with  a  fumigation  period  of  %  to  1  hr.  This  treatment, 
at  a  temperature  of  about  65°F.  and  a  low  percentage  of  atmospheric 
moisture,  should  be  given  only  after  dark.  Some  of  the  more  delicate 
varieties  of  plants  may  be  somewhat  injured  by  this,  but  in  all  probability 
much  less  than  by  the  continued  attacks  of  the  insects.  The  plants 
should  be  dry  (not  watered  recently)  at  the  time  of  treatment. 

Dormant  nursery  stock  should  be  treated  with  %  to  1  oz.  of  sodium 
cyanid  for  every  100  cu.  ft.,  for  1  hr.  The  stock  should  not  be  wet  nor 
very  closely  packed. 

For  the  fumigation  of  citrus  trees  during  their  dormant  or  most 
nearly  dormant  season  (October  to  January)  Y±  to  \Y±  oz.  of  sodium  cya- 
nid should  be  used  for  every  100  cu.  ft.  of  space  for  a  period  of  ^  to  1  hr. 
The  value  of  good  citrus  trees  is  such  that  gas-tight  tents  are  made  and 
used  for  fumigating  them. 

In  using  potassium  cyanid,  one-fourth  more  should  be  taken  as  the 
dose  than  indicated  above. 

Before  treating  any  place  to  be  fumigated,  determine  the  number  of 
cubic  feet  in  the  place  and  weigh  out  the  proper  amount  of  cyanid.  Tak- 
ing this  quantity  as  the  unit  from  which  to  determine  the  amounts  of 
sulf  uric  acid  and  water  for  this  dose,  measure  out  1J^  times  as  much  of 
the  acid  in  fluid  ounces  and  twice  as  much  water,  also  in  fluid  ounces. 
Thus  if  the  space  to  be  fumigated  calls  for  4J^  oz.  (by  weight)  of  the 
cyanid,  6%  fl.  oz.  of  the  acid,  and  9  fl.  oz.  of  water  will  constitute  the 


58  APPLIED  ENTOMOLOGY 

dose.  With  potassium  cyanid  the  proportions  of  the  materials  differ 
somewhat  from  this,  being  1-  part  of  the  cyanid,  1  part  of  the  acid  and 
3  parts  of  water. 

Granite-ware  dishes,  without  flaws  exposing  the  metal,  are  excellent 
containers  for  this  work.  They  should  be  considerably  larger  than  are 
needed  to  hold  the  dose,  and  for  large  areas  it  is  often  desirable  to  divide 
this  among  several  containers.  First,  place  the  proper  amount  of  water 
in  the  container;  then  add  the  acid  slowly  to  avoid  spattering  and  the 
production  of  too  much  heat;  lastly,  drop  in  the  cyanid,  which  it  is  desir- 
able to  have  loosely  wrapped  up  in  tissue  paper  in  order  to  gain  a  mo- 
ment's time  in  getting  out  before  the  gas  begins  to  be  given  off  freely. 

Great  care  must  be  taken  to  leave  the  place  instantly  after  adding 
the  cyanid  to  the  acid  and  water,  and  at  the  end  of  the  fumigation  period 
there  should  be  a  thorough  airing  for  at  least  a  quarter  of  an  hour  before 
entering.  If  there  are  windows,  these  should  be  opened  from  the  outside 
only,  and  under  no  circumstances  should  the  operator  enter  too  soon. 


CHAPTER  X 
THE  RELATIONSHIPS  OF  INSECTS 

Classification  may  be  defined  as  the  orderly  arrangement  of  different 
objects  into  groups.  Any  articles  can  be  classified  in  one  way  or  another: 
chairs  for  example,  can  be  brought  into  groups  according  to  the  kinds  of 
wood  of  which  they  are  made;  or  whether  they  are  upholstered  or  not; 
or  according  to  their  price,  and  any  of  these  might  be  equally  useful. 
With  living  things,  however,  the  problem  becomes  one  of  a  "natural" 
as  opposed  to  an  " artificial"  classification. 

It  is  now  the  general  belief  that  the  first  animals  were  extremely 
simple  in  structure,  and  that  in  the  course  of  generations  (and  centuries) 
variation  in  their  descendants  led  to  the  production  of  different  forms, 
and  finally  to  all  the  multitudes  of  kinds  now  in  existence.  This  devel- 
opment has  often  been  pictured  as  a  tree,  the  trunk  representing  the 
original  animals,  which,  varying  as  individuals  of  the  same  kind  always 
do,  began  after  a  time  to  show  several  distinct  lines  along  which  the 
variation  took  place.  This  would  be  represented  in  the  tree  by  the  lowest 
branching  of  the  trunk.  Each  main  limb  under  the  influence  of  the  same 
conditions  would  fork  in  its  turn,  perhaps  into  two,  perhaps  more,  and 
this  process  repeated  again  and  again  would  finally  produce  the  ter- 
minal twigs — the  present  animals.  Thus  each  twig  would  represent  all 
the  individuals  of  the  same  kind;  i.e.,  a  single  species;  those  nearest  it 
the  other  species  most  closely  related  to  it;  and  those  on  another  part 
of  the  tree,  though  species  and  also  related,  would  only  be  distantly  so, 
and  of  course,  quite  different. 

A  natural  classification  of  animals  therefore,  is  an  attempt  to  express 
the  actual  relationships  of  the  animals,  placing  nearest  each  other  those 
most  closely  related.  To  do  this,  the  total  of  their  "differences  and  re- 
semblances must  be  taken  into  account.  Classification  based  on  a  single 
character  then,  is  almost  always  unreliable.  The  division  of  insects  into 
three  main  groups  based  on  their  metamorphosis,  is  an  example  of  this, 
for  while  it  is  entirely  correct  as  a  statement  of  facts,  a  classification 
using  this  character  would  bring  near  together  many  insects  which  in 
reality  are  only  distantly  related. 

The  largest  limb  of  the  animal  tree  represents  the  original  insects, 
not  because  they  were  so  numerous  at  first,  but  because  they  now  form 
such  a  large  part  of  animal  life.  This  limb  is  usually  called  a  Class, 
while  the  still  more  comprehensive  groups  considered  in  Chapter  I  are 
called  Phyla.  These  are  the  main  divisions  of  the  tree.  In  this  case 
the  Hexapoda  is  the  name  given  to  the  insect  class. 

From  all  the  evidence  available,  the  original  insects  were  at  least 

59 


60 


APPLIED  ENTOMOLOGY 


comparatively  small,  wingless,  and  with  practically  no  metamorphosis. 
After  a  time  many  of  their  descendants  began  to  develop  wings,  and  a 
fork  of  the  Class  was  produced,  one  branch  (or  Subclass),  the  Apterygota, 
apparently  retaining  much  of  its  former  character,  while  the  other  sub- 
class became  the  Pterygota  or  winged  insects.  These  have  increased 
greatly  in  abundance,  and  their  variations  have  resulted  in  the  produc- 
tion of  many  branches  passing  outward  toward  the  twigs,  named  in 
sequence,  Orders,  Families,  Genera  and  Species.  Intermediate  branch- 
ings between  these  often  also  need  recognition  and  are  called  Suborders, 


Mecopi-era- 


Ho  mop  fere?-  - — - 
Jizmipfera 


Anoplura 

Malfaphaga--*, 
Corrode ntf a- 


HexQpod 


/    Siphonapfara 

inchop-rera 


•Sfrepsip'farcr 
Cokophra 

'Dermaphra 

'Emb'iidina 
"Pkcophra 


Ephemerida 


f-'TTiusarwra 

Collembo/a 


FIG.  34. — Diagram  suggesting  possible  relations  of  the  orders  of  insects  to  each  other, 
expressed  in  a  tree-like  way:  the  Hexapod  limb. 

Superfamilies,  etc.,  as  may  be  necessary.  The  twigs  each  represent  a 
single  species,  but  here  we  may  recognize  subspecies,  varieties,  races,  etc., 
among  which  the  individuals  which  together  constitute  the  species,  are 
distributed. 

In  any  consideration  of  the  different  groups  of  insects  one  must 
necessarily  follow  after  another  through  the  book,  and  when  four  groups 
for  example,  are  equally  near  relatives,  the  first  and  fourth  treated  may 
thereby  appear  more  distant  than  is  really  the  case. 

Between  the  fork  of  the  insect  limb  which  produced  the  Apterygota 
and  the  Pterygota,  and  the  twigs  representing  the  species,  the  actual 


THE  RELATIONSHIPS  OF  INSECTS 


61 


divisions  of  the  branches  are  more  or  less  uncertain.  The  species  in 
general,  group  themselves  quite  easily  into  different  genera  and  these 
into  families;  but  while  these  last  can  in  most  cases  be  definitely  placed 
in  their  orders,  their  correct  relation  to  each  other  is  often  debatable. 
The  relation  of  the  orders  to  each  other  is  far  from  settled,  and  while 
some  are  evidently  more  closely  allied  than  others,  within  certain  limits 
one  order  could  follow  another  in  almost  any  sequence  without  any  serious 
loss  to  the  expression  of  relationships.  Where  orders  appear  to  be  closely 
allied  to  each  other,  this  will  be  indicated  in  connection  with  their 
consideration. 

With  the  relations  between  the  orders  and  also  the  families  within 
the  orders,  still  uncertain  in  many  cases,  a  tree  showing  these  must  of 
necessity  express  only  the  views  of  the  individual  who  drew  it.  Such  a 
tree  carried  to  the  species  would  be  entirely  too  large  for  these  pages 
(there  are  about  80  families  of  beetles,  and  many  of  the  other  orders  have 
large  numbers  also),  but  one  carried  to  the  orders  is  given  here  (Fig.  34) 
to  illustrate  the  general  idea  of  a  tree-like  classification. 

Expressed  in  tabular  form,  the  classification  followed  in  this  book 
is  given  below. 

CLASS  SUBCLASS  ORDER  SUBORDER  COMMON  NAME,  OR  EXAMPLES 

Apterygota  /  Thysanura Silver  fish,  etc. 

\  Collembola Snow  fleas,  etc. 


Hexapoda 


Pterygota 


Ephemerida . . . 

Odonata 

Plecoptera .... 
Embiidina.  . 


Orthoptera . . . 


Isoptera 

Dermaptera 

f  Rhynchophora . 
Coleoptera<   ~  , 

[  Coleoptera  vera 

Strepsiptera 

Thysanoptera 

Corrodentia 

Mallophaga 

Anoplura 

Hemiptera 

Homoptera 

Neuroptera 

Trichoptera 

(  Heterocera. . . 
Lepidoptera  <  „,        , 

(  Rhopalocera . .  . 

Mecoptera 

Diptera 

Siphonaptera 

Hymenoptera 


.  May-flies 

.  Dragon-flies 

.  Stone  flies 

.  (No  common  name  nor 
examples) 

.Roaches,  grasshoppers, 
crickets,  etc. 

.  Termites  or  White  ants 

.  Earwigs 

.  Snout  beetles 

.  True  beetles 

.  Stylopids 

.  Tlirips 

.  Book  lice;  Psocids 

.  Bird  lice  (biting) 

.  Sucking  lice 

.  True  Bugs 

.Scales,  plant  lice,  leaf  hop- 
pers, etc. 

.Corydalis,  aphis  lions,  ant 
lions,  etc. 

.  Caddis  flies 

.  Moths 

.  Butterflies 

.  Scorpion  flies 

.Flies 

.Fleas 

.Saw  flies,  ichneumon  flies, 
ants,  wasns.  hees.  etr». 


CHAPTER  XI 
THE  APTERYGOTA 

These  are  all  relatively  small  insects,  some  being  nearly  microscopic 
in  size,  while  the  largest  are  seldom  more  than  an  inch  in  length.  They 
are  all  land  animals  though  a  few  live  near  the  ocean  and  are  occasion- 
ally found  in  tide  pools.  They  are  widely  distributed  over  the  earth, 
some  living  in  arctic  conditions  while  others  occur  in  the  tropics,  but 
nearly  all  at  least,  require  a  somewhat  humid  atmosphere. 

In  this  group  the  mouth  parts  seem  to  be  typically  of  the  chewing 
type.  In  many  cases  they  are  as  much  exposed  as  in  most  insects,  but 
in  some  they  appear  to  have  been  drawn  into  the  head  so  that  when  not 
in  use  they  are  almost  entirely  concealed.  Under  such  conditions  they 
are  often  so  slender  as  to  be  no  longer  of  value  for  chewing,  and  are 
possibly  used  for  rasping  and  sucking  food. 

Some  Apterygota  have  traces  of  abdominal  legs  ("vestigial  legs"). 
Spine-like  appendages,  attached  to  the  hinder  margins  of  some  of  the 
abdominal  segments  beneath  and  called  styli,  may  also  occur.  A 
ventral  tube  present  in  some  Apterygota  on  the  underside  of  the  first 
abdominal  segment  may  be  simply  a  small  projection  partially  divided 
into  two,  or  it  may  be  highly  developed  into  two  slender  but  delicate 
tubes  which  can  be  extended  to  a  considerable  distance.  Its  use  is  not 
known. 

Bringing  together  these  facts,  the  Apterygota  may  be  characterized 
as: 

Wingless  insects  having  the  mouth  parts  either  exposed  and  of  the  chewing 
type,  or  drawn  into  a  cavity  within  the  head  where  they  are  sometimes  so 
slender  as  to  be  of  no  value  for  chewing  but  could  possibly  be  used  for  sucking. 
In  those  with  exposed  mouth  parts,  more  then  one  pair  of  styli  is  present  on 
the  back  margins  of  the  hinder  abdominal  segments:  in  those  with  mouth 
parts  drawn  into  the  head,  styli,  a  ventral  tube  or  traces  of  abdominal  legs 
are  present. 

Very  few  of  the  Apterygota  are  of  any  importance  from  an  economic 
standpoint,  but  they  are  of  much  interest,  being  the  simplest  insects 
known  and  throwing  some  light  upon  the  subject  of  the  ancestry  of  the 
insect  group. 

Two  subdivisions,  the  orders  Thysanura  and  Collembola,  are  generally 
recognized  in  the  Apterygota.  The  Thysanura  have  styli  present, 
while  in  the  Collembola  they  are  absent.  Cerci,  which  are  segmented, 

62 


THE  APTERYGOTA 


63 


antenna-like  projections  backward  from  the  end  of  the  abdomen,  occur 
in  the  Thysanura.  Here  they  are  two  in  number,  rather  long  and  con- 
sisting of  many  segments,  except  in  a  few  cases  where  they  have  been 
transformed  into  a  pair. of  good  sized,  unsegmented  forceps.  In  the 
Collembola,  cerci  are  either  entirely  absent  or  very  small  and  consist 
of  only  one  segment. 

THE  THYSANURA 

The  Thysanura  average  much  larger  than  the  Collembola.  They  are 
characterized  as: 

Apterygota  with  styli  on  the  underside  of  the  abdomen,  and  with  usually 
long,  many-segmented  cerci  at  the  end  of  the  body,  except  in  a  few  species 
where  these  have  become  a  pair  of  forceps. 

Only  one  Thysanuran  is  of  particular  eco- 
nomic importance  in  the  United  States;  the 
Silver  Fish  or  "Slicker"  (Fig.  35). 

The  Silver  Fish  (Lepisma  saccharina  L.). — 
This  little  household  pest  is  found  both  in 
Europe  and  this  country.  It  is  silvery  gray  in 
color,  usually  less  than  half  an  inch  long,  and 
very  active  and  hard  to  catch.  Besides  the  two 
long  cerci  at  the  hinder  end  of  the  body  it  has  a 
similar  " caudal  filament"  giving  the  insect  the 
appearance  of  having  three  "tails."  It  prefers 
dark  places  and  feeds  on  book  bindings, 
starched  clothing,  or  anything  containing  starch, 
and  often  loosens  wall  paper  by  feeding  on  the 
starch  used  to  paste  it  to  the  wall. 

It  may  be  controlled  by  placing  on  pieces  of 
card,  starch  paste  made  as  follows:  Flour  1 

pint;  Arsenic  %  to  %  oz.;  water  enough  to  make  a  thin  paste  after 
boiling.  Spread  this  on  the  cards  and  place  near  where  the  insects  are 
found,  for  them  to  feed  upon.  Do  not  place  the  cards  where  young 
children  can  get  at  them.  The  Silver  Fish  prefers  moist  to  dry  places, 
so  clothing  should  not  be  stored  where  it  is  damp.  Sometimes  Insect 
Powder  dusted  in  the  haunts  of  this  pest  is  helpful. 

THE  COLLEMBOLA 

The  Collembola  are  usually  very  small  insects,  and  being  dark  colored, 
in  most  cases  are  not  often  noticed.  Most  of  this  group  have  a  "spring" 
attached  near  the  hinder  end  of  the  body  beneath.  This  consists  of  a 
single  piece  to  which  a  pair  of  others  are  joined  and  the  whole  is  carried 
pointing  forward  when  not  in  use  (Fig.  36).  When  the  spring  is  suddenly 
pressed  against  the  ground,  the  entire  body  of  the  insect  is  thrown  into  the 
air  and  a  peculiar  hopping  or  leaping  motion  results. 


FIG.  35.— Silver  Fish 
(Lepisma  saccharina  L.) 
about  twice  natural  size. 
(After  14th  Rept.  Minn. 
State  Entomologist.) 


64 


APPLIED  ENTOMOLOGY 


The  Collembola  may  be  characterized  as: 

Apterygota  without  styli  on  the  underside  of  the  abdomen:  cerci  either 
absent  or  very  small  and  consisting  of  only  one  segment.  Usually  much 
smaller  than  Thysanura  and  most  of  them  with  a  ventral  "spring." 


FIG.  36. — Springtail  (Papirius  fuscus  Lucas)  showing  forked  "spring"  projecting  forward 
toward  the  head  beneath  the  body.     Greatly  enlarged.     From  Lubbock.) 

The  most  familiar  members  of  this  order  are  probably  the  Snow 
Fleas,  which  are  sometimes  seen  in  enormous  numbers  on  snow,  where 
their  dark  color  and  their  hopping  movements  make  them  noticeable 
(Fig.  37).  Some  of  the  group  often  become  a  nuisance  by  gathering 


Real  length  34  2  i 


FIG.  37. — Snow  Flea   (Achorutes  .nivicola  Fitch)  greatly  enlarged. 

(From  Folsom.) 

in  maple-sap  buckets  on  trees  being  tapped.  Some  also,  feed  on  the  leaves 
of  plants  making  tiny  holes,  which  though  of  themselves  unimportant  be- 
ing small,  still  afford  the  spores  of  fungous  diseases  excellent  opportunities 
for  entrance  to  the  plant  tissues.  In  cases  where  work  of  this  nature  by 
Collembola  is  sufficient  to  warrant  it,  spraying  the  leaves  as  soon  as  the 
injury  appears,  with  arsenate  of  lead,  standard  formula,  is  effective. 


CHAPTER  XII 
THE  PTERYGOTA.     THE  EPHEMERIDA 

The  group  Pterygota  includes  practically  all  our  common  insects 
and  is  the  main  branch  of  the  class  Hexapoda,  the  Apterygota  though 
of  equal  rank,  being  a  mere  twig  in  size,  in  comparison. 

As  a  whole  the  Pterygota  are  characterized  by  the  presence  of  wings, 
though  as  already  indicated,  many  of  them  for  one  reason  or  another 
have  lost  these  structures. 

Almost  all  characters  present  in  insects  may  be  found  in  this  section 
without  referring  to  the  Apterygota:  practically  all  the  pests  and  all  the 
beneficial  forms  belong  here;  and  their  differences  are  so  great  that  22 
orders  have  been  established  as  subdivisions  for  them. 

The  earliest  writers  on  insects  did  not  regard  these  differences  as  of 
great  importance,  and  called  the  groups  families  or  gave  them  even  lower 
rank.  More  recent  workers,  however,  have  regarded  them  as  of  greater 
significance,  some  students  of  the  subject  being  inclined  to  recognize  more, 
rather  than  fewer  orders,  and  it  is  not  at  all  unlikely  that  time  will  finally 
bring  a  general  acceptance  of  26  or  28  such  groups  instead  of  the  first  seven 
established  by  Linne,  or  the  22  here  treated. 

THE  EPHEMERIDA 

The  Ephemerida,  May-flies  or  shad-flies  as  they  are  often  called 
(Fig.  38),  are  insects  of  medium  or  small  size.  The  adults  have  delicate 
bodies  and  gauzy,  fragile  wings,  the  latter  usually  with  many  cross- veins. 
The  fore  wings  are  much  larger  than  the  hind  ones,  which  in  some  cases 
are  absent,  and  the  former  are  in  general,  rather  strongly  triangular  in 
outline.  When  at  rest  they  are  held  vertically  above  the  body.  At 
the  end  of  the  abdomen  two  or  three  long  threads,  each  composed  of 
many  segments  and  often  called  caudal  filaments,  are  usually  present, 
the  lateral  ones  being  cerci  corresponding  to  those  in  the  Thysanura. 

The  mouth  parts  of  the  adult  May-fly  are  of  the  chewing  type,  but 
so  poorly  developed  that  it  is  doubtful  if  they  are  ever  made  use  of. 
In  some  cases  they  are  even  rudimentary.  The  reproductive  organs 
differ  from  those  in  all  the  other  groups,  the  ducts  being  not  united  on  the 
middle  line  below,  but  opening  separately  to  the  outside — apparently 
the  retention  of  a  very  primitive  condition.  The  early  stages  are  passed 
in  the  water,  the  nymphs  breathing — at  least  after  the  first  few  molts— 
by  tracheal  gills.  These  are  delicate,  usually  wing-like  in  form,  and  are 
5  65 


66 


APPLIED  ENTOMOLOGY 


outgrowths  of  the  body  wall.  Into  them  pass  tracheal  trunks  which 
branch  again  and  again  so  that  only  their  own  walls  and  those  of  the  gill 
itself  separate  the  air  in  the  tracheae  from  that  in  the  water  outside,  and 
so  thin  are  these  layers  that  the  oxygen  in  the  water  can  pass  through 
them  into  the  tracheae,  and  carbonic  acid  gas  pass  out. 

These  insects  add  to  their  list  of  peculiarities  also,  the  fact  that  after 
becoming  full  grown  and  being  able  to  fly,  they  molt  once  more,  even  a 
thin  layer  over  the  final  wings  being  shed.  $ub;>>M^ 


r 


\ 


FIG.  38. — Adult  May-fly  (Hexagenia  varidbilis  Eaton)   showing  the  long  cerci.     N.atural 

size.     (From  Folsom.) 

From  these  statements  the  group  may  be  characterized  thus: 
Inserts  having  as  adults  delicate  bodies  and  usually  four  wings,  the 
front  pair  much  larger  than  the  others  (which  are  sometimes  absent),  and 
generally  with  many  cross-veins:  end  of  the  abdomen  with  two  or  three  long, 
caudal  filaments  composed  of  many  segments:  reproductive  organs  with  two 
openings  to  the  exterior:  mouth  parts  of  the  chewing  type  but  practically 
rudimentary:  nymphs  living  in  water  and  with  an  incomplete  metamor- 
phosis, the  final  molt  coming  after  the  wings  have  become  fully  developed. 
May-flies  are  most  abundant  near  streams  and  lakes,  as  their  nymphs 
live  in  the  water.  The  fully  mature  nymphs  leave  the  water,  usually 
in  greatest  numbers  about  sunset,  and  suddenly  molting,  extend  their 
wings  and  fly  off,  but  as  above  stated  usually  molt  again  within  a  few 
hours.  As  their  flight  generally  begins  about  dusk  and  as  they  are 
strongly  attracted  to  lights,  they  are  often  seen  in  multitudes  around 
street  lights  during  the  evenings. 


THE  PTERYGOTA.      THE  EPHEMERIDA  67 

The  adults  live  only  a  few  hours — not  more  than  a  day  or  two  at 
most — but  during  this  time  the  eggs  are  dropped  into  the  water.  The 
nymphs  which  hatch  from  them  feed,  probably  mainly  on  vegetable 
matter  at  the  bottom,  though  some  are  doubtless  partly  carnivorous. 
They  live  for  one,  two  or  three  years,  according  to  the  species  concerned 
(some  have  two  generations  each  year) ,  feeding,  and  molting  with  unusual 
frequency  for  insects  (Lubbock  observed  21  molts  in  one  species),  until 
they  are  full-grown.  During  this  time  the  mouth  parts  are  well  developed 
and  of  the  chewing  type,  but  in  the  adult  they  become  practically  useless. 

These  insects  are  of  no  economic  importance  except  perhaps  to  a 
very  slight  degree  as  scavengers  in  the  water,  feeding  on  matter  that 
might  otherwise  decay  and  become  objectionable,  but  their  value  for 
this  is  probably  small  at  best.  They  are  fed  upon  as  larvae  and  to 
some  extent  as  adults,  by  fish  and  some  carnivorous  insects  of  other 
groups,  and  for  this  reason  also  may  be  rated  as  slightly  beneficial. 
At  present  about  500  kinds  are  known,  but  the  group  has  not  been  very 
thoroughly  studied.  Many  fossil  Ephemerids  have  been  found,  which 
suggests  that  the  insects  are  possibly  less  abundant  now  than  was  once 
the  case. 


CHAPTER  XIII 
THE  ODONATA 

The  Odonata  are  such  large  and  noticeable  insects  that  they  have 
received  many  common  names,  such  as  dragon-flies,  snake-doctors, 
devil's  darning  needles,  snake-feeders,  etc.  They  are  most  plentiful 
near  water,  as  in  this  they  spend  their  early  lives,  though  the  larger 
and  more  powerful  members  of  the  group  are  frequently  seen  flying  high 
in  the  air  and  at  some  distance  from  their  more  usual  habitat. 

The  dragon-flies  have  rather  long,  slender  bodies,  the  abdomen  being 
less  shortened  by  the  fusion  and  telescoping  of  its  segments  than  in 
most  insects.  The  head  is  large,  generally  rather  spherical,  though  con- 
cave behind,  and  a  great  part  of  its  surface  is  occupied  by  two  very  large 
compound  eyes,  each  of  which  in  some  species,  contains  more  than 
30,000  facets.  As  these  insects  are  carnivorous  and  capture  their  prey 
as  it  is  flying,  the  advantage  of  large  eyes  which  are  also  because  of  the 
curvature  of  the  surface  of  the  head,  capable  of  seeing  in  almost  every 
direction,  is  evident.  There  are  also  three  ocelli.  The  antennae  are 
short  and  not  very  noticeable. 

The  mouth  parts,  which  are  of  the  chewing  type,  are  large  and  well 
developed.  The  food  appears  to  be  captured  by  the  legs  and  held  by 
them  while  it  is  being  eaten. 

Four  wings  are  present,  all  of  about  equal  size,  though  the  hinder 
pair  are  somewhat  larger  except  in  the  section  known  as  the  Damsel- 
flies.  The  main  veins  are  stout  and  are  connected  by  many  cross-veins. 
Near  the  middle  of  the  costa  of  each  wing  is  a  slight  notch  called  the 
nodus,  at  which  point  there  is  a  particularly  stout  cross-vein.  When  at 
rest  the  wings  are  held  either  nearly  vertical  over  the  body  (damsel-flies) 
or  extended  laterally,  much  as  in  flight.  The  metamorphosis  is  by  pro- 
gressive changes  at  times  of  molting,  and  though  the  nymph  can  hardly 
be  said  to  ever  greatly  resemble  the  adult,  development  may  be  con- 
sidered as  being  by  an  incomplete  metamorphosis. 

The  Odonata  may  then  be  characterized  as: 

Insects  which  as  adults  usually  have  long,  slender  bodies,  large  heads  and 
large  eyes:  wings  four,  membranous,  the  hinder  pair  as  large  or  larger  than 
the  front  pair,  and  each  has  near  the  middle  of  its  front  margin  a  notch, 
somewhat  resembling  a  joint,  called  the  nodus:  mouth  parts  for  chewing  and 
well  developed.  Metamorphosis  incomplete. 

There  are  two  groups  of  dragon-flies.  In  one  the  insect  is  slender, 
the  two  pairs  of  wings  are  of  about  equal  size,  and  when  not  in  use  are 

68 


THE  0  DON  AT  A 


69 


held  almost  vertically  above  the  body  (Fig.  39).     These  insects  are  often 
called  damsel-flies.     In  the  other  group  the  body  is  stouter  and  propor- 


FIG.  39. — Damsel-fly  (Lestes  uncata  Kirby)  showing  position  of  wings  when  at  rest.     (After 
Needham,  N.  Y.  State  Mus.  Bull.  68.) 


FIG.  40. — Dragon-fly  (Anax  junius  Dru.)-     Natural  size.     (Original.') 

tionally  shorter,  and  the  wings  when  at  rest  extend  out  horizontally  at 
the  sides  of  the  body  (Fig.  40). 


70 


APPLIED  ENTOMOLOGY 


The  bodies  of  dragon-flies  are  often  brilliantly  colored,  and  in  some 
cases  covered  with  a  "  bloom,"  giving  them  a  whitish  appearance  (Fig. 
41).  The  adults  feed  on  practically  almost  any  flying  insects  smaller 
than  themselves  which  they  may  capture  during  their  flight.  Flies  and 


i 


FIG.  41. — Dragon-fly    (Plathemis   lydia    Dru.)    showing   "bloom"   on  abdomen.     About 

natural  size.     (Original.) 

mosquitoes  form  a  favorite  food,  and  the  attempt  has  been  made  to 
"tame"  dragon-flies  and  keep  them  in  houses  on  this  account,  but  with- 
out success.  They,  are  very  voracious,  one  specimen  having  been  known 
to  consume  40  house-flies  in  less  than  two  hours. 

Many  dragon-flies  fly  very  swiftly  either  in  direct  lines  or  making 
sudden  changes  of  direction  while  hunting  their  prey,  and  are  perhaps 


FIG.  42. — Nymph  of  a  Dragon-fly    with    mask  extended   forward. 

(Original.) 


Enlarged  one-third. 


unequalled  in  this  regard  by  any  other  insects.  They  also  mate  in  the 
air.  The  eggs  are  laid  either  in  the  water,  attached  to  water  plants,  or 
in  the  stems  of  plants  under  water.  In  the  latter  case  they  are  laid  singly 
but  otherwise  they  are  usually  in  clusters  containing  either  a  small  or  a 
large  number  of  eggs. 

The  eggs  may  hatch  after  a  few  days,  or  if  laid  in  the  fall,  may  not 
produce  nymphs  until  the  following  spring.     The  young  nymphs  stay 


THE  O  DO  NAT  A  71 

at  the  bottom  of  the  water  and  are  carnivorous,  feeding  on  larger  and 
larger  animals  as  they  grow,  individuals  of  the  largest  species  attacking 
small  fish  in  some  cases,  though  the  bulk  of  their  food  is  undoubtedly 
the  aquatic  larvse  of  insects.  They  lie  on  the  bottom  waiting  for  their 
prey  to  come  within  reach,  and  when  it  is  near  enough  they  thrust  out 
the  under-lip  (labium)  and  seize  it  (Fig.  42).  This  labium  has  been 
remarkably  developed  from  its  usual  form,  being  drawn  out  into  two  long 
pieces  with  a  pair  of  jaws  or  claws  at  the  end.  When  not  extended  the 
piece  connected  at  one  end  with  the  head  is  bent  backward  under  the 
body,  while  the  second  piece,  hinged  to  the  other  end  of  the  first,  extends 
forward  so  that  its  front  end  with  the  jaws  lies  near  the  front  of  the  head, 
which  it  somewhat  conceals,  and  this  has  led  to  calling  the  structure  a 
"mask."  When  this  is  extended  forward  it  reaches  out  more  than  twice 
the  length  of  the  head,  thus  enabling  the  nymph  to  capture  animals  which 
are  not  very  close  to  it. 

Breathing  in  the  nymphs  of  the  damsel-flies  appears  to  be,  in  part  at 
least,  by  means  of  long  and  rather  large,  tracheal  gills  at  the  end  of  the 
abdomen,  which  are  also  used  for  swimming.  In  the. other  section  of 
the  Order,  the  gills  are  found  in  the  rectum,  into  which  water  is  drawn, 
bathing  the  gills  there,  after  which  it  is  expelled,  and  if  this  is  done  quickly 
the  recoil  carries  the  nymph  forward,  thus  providing  one  means  of 
locomotion. 

Molts  are  frequent,  and  when  full-grown  the  nymph  crawls  out  of 
the  water  and  molts  for  the  last  time,  whereupon  the  wings  grow  to  full 
size  and  the  adult  insect  is  produced.  Some  dragon-flies  have  two 
generations  a  year  or  possibly  even  more,  while  in  other  cases  more  than 
a  year  is  necessary  to  a  generation,  but  one  each  season  is  the  usual 
condition. 

Despite  tradition  and  their  bad  reputation,  dragon-flies  are  in  no 
way  injurious  .to  man,  not  stinging — they  have  nothing  to  sting  with — 
nor  biting  to  such  an  extent  as  to  cause  the  slightest  pain,  their  jaws 
being  too  weak  to  even  break  the  skin.  They  are  beneficial  insects 
both  as  young  and  adults,  so  much  of  their  food  consists  of  injurious 
insects  such  as  flies,  mosquitoes,  etc.,  while  the  injury  they  cause  by 
feeding  on  fish  is  usually  so  slight  as  to  be  negligible. 

Dragon-flies  are  sun-loving  animals,  concealing  themselves  during 
dark,  cloudy  weather  Between  5,000  and  10,000  kinds  are  known,  and 
the  greatest  number  of  these  occur  in  the  warmer  regions.  Fossil  dragon- 
flies  or  insects  resembling  them  are  numerous,  and  some  of  them  were 
very  large,  one  measuring  more  than  two  feet  from  wing-tip  to  wing-tip. 


CHAPTER  XIV 


THE    PLECOPTERA 

The  most  usual  common  name  for  the  Plecoptera  is  the  Stone-flies. 
They  range  from  small  to  good-sized  insects  whose  bodies  are  quite  long, 
flattened  and  with  rather  parallel  sides.  The  wings  are  nearly  always 
well  developed  and  with  many  cross-veins,  though  in  a  few  cases  they  are 
very  small  and  in  some  species  the  cross-veins  are  few.  Considering 
only  the  more  usual  condition,  the  fore  wings  extend  well  behind  the 
end  of  the  body  when  closed  and  have  a  considerably  smaller  area  than 
the  hind  wings  which  are  so  broad  that  when  they  are  at  rest  upon  the 
upper  side  of  the  body  they  must  be  folded  lengthwise  into  plaits  to 
reduce  them  to  the  necessary  width  (Fig.  43). 


FIG.  43. — Adult    Plecopteran    (Pteronarcys    regalis 

Folsom.) 


Newm.).     Slightly  reduced.     (From 


The  antennae  are  long  and  composed  of  many  segments.  In  most 
members  of  the  group  a  pair  of  cerci  is  present  at  the  end  of  the  abdomen. 
The  mouth  parts  are  of  the  chewing  type  but  are  generally  so  weakly 
developed  as  to  be  practically  useless.  The  larvae  live  in  water  and  do 
not  differ  greatly  in  appearance  from  the  adults. 

The  group  may  be  described  as  follows: 

Insects  which  as  adults  have  four  membranous  wings,  usually  longer 
than  the  body,  and  generally  with  many  cross-veins.  Hind  wings  larger 
than  the  front  ones  and  when  at  rest  folded  lengthwise  and  lying,  covered  by 
the  front  pair,  on  the  abdomen.  Antenna  long:  a  pair  of  caudal  cerci 
usually  present:  mouth  parts  for  chewing  but  generally  poorly  developed. 
Metamorphosis  incomplete. 

72 


THE  PLECOPTERA  73 

Adult  stone-flies  are  most  numerous  near  streams  and  particularly 
those  with  a  rapid  current.  The  eggs  which  are  often  several  thousand 
in  number,  are  laid  in  the  water  and  the  nymphs  locate  on  the  underside 
of  stones.  Some  breathe  through  the  surface  of  the  body.  Tracheal 
gills,  when  present,  are  not  leaf-like  as  in  the  May-flies  but  are  tufts  of 
numerous  short,  thread-like  structures  containing  tracheae,  a  tuft  or 
bundle  just  behind  each  leg,  on  the  underside,  and  also  on  the  first  two 
abdominal  segments.  When  fully  grown  the  nymphs  leave  the  water 
and  molt  for  the  last  time  on  land.  They  feed  on  small  insects,  probably 
largely  May-fly  nymphs,  and  possibly  on  vegetable  matter  (diatoms) 
and  are  themselves  a  favorite  food  for  fish. 

Some  species  of  stone-flies  appear  in  enormous  numbers  just  as  the 
ice  is  breaking  up  in  the  streams,  in  the  northern  United  States,  and  others 
are  found  on  the  snow  even  earlier  in  the  season,  on  warm  days.  In 
general  the  group  is  without  economic  importance,  but  a  few  kinds  of 
adults  have  recently  been  observed  injuring  the  buds  and  foliage  of  fruit 
trees  as  these  first  develop,  in  the  northwest,  and  in  these  species  the 
mouth  parts  are  much  more  strongly  developed  than  in  the  others. 
Only  2,000  to  3,000  species  are  known. 


CHAPTER  XV 
THE  EMBIIDINA 

This  is  a  small  group  of  insects,  only  about  60  species  having  been 
described.  They  live  in  warm  climates  either  under  stones  or  on  plants 
in  crevices  of  the  bark  or  elsewhere,  spinning  silken  tunnels  in  which  to 
live.  The  largest  species  known  is  less  than  an  inch  long  (Fig.  44). 

The  wings  are  generally  (always?)  present  in  the  males  and  absent 
in  the  females.  The  tunnels  appear  to  be  formed  at  least  partly  for 
protection,  but  perhaps  also  to  aid  in  preserving  moisture,  for  when  dry 


FIG.  44. — Emlria  major  Imms,  about  1%  times  natural  size. 

Linn.  Soc.  Land.  1913.) 


(Reduced  from  Imms.  Trans. 


weather  comes  on  they  are  carried  deeper  into  the  soil  in  the  ground- 
inhabiting  forms.  The  silk  appears  to  be  produced  by  glands  located 
in  the  tarsi  of  the  fore  legs — something  unparalleled  elsewhere  among 
insects.  The  mouth  parts  are  of  the  chewing  type. 

The  food  of  these  insects  is  probably  vegetable  matter,  but  the  injury 
they  do  to  plants,  as  thus  far  reported,  is  not  great.  Even  where  they 
are  most  abundant  they  are  seldom  seen  except  by  those  looking  for 
them.  A  few  fossil  specimens  belonging  to  this  group  have  been  found 
preserved  in  amber.  The  Embiids  appear  to  be  more  closely  related  to 
the  Plecoptera  than  to  any  of  the  other  orders  of  insects. 


74 


CHAPTER  XVI 
THE  ORTHOPTERA 

The  Orthoptera  is  a  large  group  of  insects  containing  over  10,000 
species.  Many  of  them  are  very  large  and  striking  in  appearance  and 
common  names  have  been  given  to  different  families  in  the  order,  bub 
none  to  it  as  a  whole. 

The  insects  of  this  order  are  so  diverse  in  structure,  appearance  and 
habits  that  it  is  difficult  to  give  distinctive  characters,  but  they  all 
have  well-developed  chewing  mouth  parts.  The  majority  of  them  have 
four  wings,  the  front  pair  being  slightly  thicker  than  the  others,  somewhat 
leathery  in  texture,  and  overlapping  more  or  less  when  folded.  The 
hind  wings  are  almost  always  larger  and  fold  in  plaits.  In  many  of  the 
group,  however,  the  wings  are  lacking  or  very  small,  in  which  case  it  is 
difficult  to  determine  whether  the  insect  is  an  adult  or  a  nymph,  without, 
or  with  only  partially  developed  wings. 

In  some  of  the  families  the  hind  legs  are  much  developed  and  the 
insects  have  the  power  of  jumping:  in  others  this  is  not  the  case  and 
walking  and  running  are  their  methods  of  locomotion  on  the  ground. 
On  this  basis  the  Order  has  often  been  divided  into  two  sections,  Cursoria 
or  running  Orthoptera,  and  Saltatoria  or  leaping  Orthoptera. 

The  Orthoptera  may  be  denned,  despite  the  difficulties  above  indi- 
cated, as: 

Insects  which  when  adult  have  mouth  parts  for  chewing;  usually  four 
wings,  the  front  pair  thicker  than  the  others;  the  hind  pair  larger  and  folded 
in  plaits  when  at  rest.  A  pair  of  cerci  is  always  present.  Metamorphosis 
incomplete. 

Many  students  of  the  group  are  of  the  opinion  that  the  insects 
included  in  this  order  should  really  be  placed  in  two  or  three,  but  at 
present  such  a  separation  seems  hardly  advisable.  Most  of  the  families  are 
quite  distinct.  The  group  is  frequently  divided  into  eight  or  ten  families, 
but  for  the  purposes  of  this  book,  six  will  be  considered.  These  are: 

(  Blattidse,  Roaches. 

Cursoria  ]  Mantidae,  Mantids. 

I  Phasmidse,  Walking  Sticks. 

r  Acrididae,  Locusts  and  Short-horned  Grasshoppers. 

Saltatoria   \  Tettigoniidae,  Long-horned  Grasshoppers  and  Katydids. 

I  Gryllidae,  Crickets. 

75 


76  APPLIED  ENTOMOLOGY 

Family  Blattidae  (The  Roaches) 

These  insects  are  known  by  a  variety  of  common  names  such  as 
roaches,  cockroaches,  water-bugs,  and  black-beetles.  The  group  is 
primarily  one  living  in  warm  countries  with  many  kinds  living  in  houses, 
and  many  more,  some  of  them  several  inches  in  length,  occurring  wild. 
In  more  northern  climates  only  a  few  are  wild  and  four  are  household 
pests;  these  last  when  adult  ranging  from  less  than  an  inch  to  nearly 
two  inches  in  length.  In  the  north  the  wild  species  are  found  under 
logs  and  stones  and  never  enter  houses.  They  are  pale  brown  and  the 
winged  adults  are  an  inch  or  slightly  more  in  length. 

Roaches  are  generally  brown  or  dark  colored,  though  some  are 
green.  They  are  broad  and  flattened,  with  the  head  bent  under  the  body 
so  that  the  mouth  opens  backward  and  the  eyes  look  downward.  The 
antennae  are  long,  slender  and  of  many  segments.  Wings  are  usually 
developed  in  the  adults  and  the  hinder  pair  fold  once.  The  mouth 
parts  are  strong  and  the  legs  are  long,  and  bear  many  spines.  Roaches 
are  active  at  night,  hiding  in  dark  places  such  as  cracks  and  crevices 
during  daylight,  and  can  run  rapidly. 


FIG.  45. — Egg  case  of  American  Roach:  a,  side;  b,  end  view.     Both  considerably  enlarged. 
(Modified  from  U.  S.  D.  A.  Farm.  Bull.  658.) 

The  household  pests  of  this  group  consume  foods  and  food  materials 
freely;  gnaw  woolen  goods,  leather,  and  anything  which  has  paste 
on  it,  and  thus  often  injure  book  bindings;  in  fact  they  are  practically 
omnivorous.  Besides  eating,  they  leave  a  disagreeable  "roachy"  odor 
which  spoils  food  where  they  have  been.  When  abundant  they  become 
very  troublesome  and  vigorous  measures  must  be  taken  for  their  control. 
They  lay  their  eggs  in  packets,  the  number  per  packet  varying  with  the 
species,  and  the  outside  case  is  horny  in  nature  (Fig.  45).  This  case 
may  be  carried  around  partly  projecting  from  the  body  of  the  parent  for 
several  days  or  even  weeks.  The  young  are  active,  feed  freely  and  molt 
several  times,  but  it  is  doubtful  if  there  is  more  than  one  generation  a 
year,  at  least  in  the  northern  United  States. 

HOUSE  ROACHES 

The  German  Roach  (Blatella  germanica  L.). — This  insect,  often 
called  the  Croton  bug,  came  from  Europe  and  is  generally  the  most 
common  of  the  house  roaches  in  the  eastern  United  States  (Fig.  46). 


THE  ORTHOPTERA 


77 


FIG.  46. — German  Roach  or  Croton  Bug  (Blatella  germanicaL.).    c,  egg  case  much  enlarged 
e,  adult,  natural  size;  /,  adult  carrying  egg  case.     (From  U.  S.  D.  A.  Farm.  Bull.  658.) 


FIG.  47. — American   Roach   (Periplaneta  americana  L.)   adults:  a,   from  above;  6,  from 
beneath,  about  natural  size.     (Modified  from  U.  S.  D.  A.  Farm.  Bull.  658.) 


FIG.  48.  FIG.  49. 

FIG.  48. — Australian  Roach  (Periplaneta  australasice  Fab.).  Adult,  about  two-thirds 
natural  size.  (Reduced  from  U.  S.  D.  A.  Farm.  Bull.  658.) 

FIG.  49. — Oriental  Roach  (Blatta  orientalis  L.)  adults  about  two-thirds  natural  size: 
a,  female;  b,  male.  (Reduced  from  U.  S.  D.  A.  Farm.  Bull,  658.) 


78  APPLIED  ENTOMOLOGY 

The  adult  is  from  one-half  to  three-fourths  of  an  inch  long,  pale  brown 
with  two  darker  brown  stripes.  It  is  very  active  and  increases  in 
numbers  very  rapidly. 

The  American  Roach  (Periplaneta  americana  L.). — This  is  the  largest 
of  the  house  roaches,  being  from  one  and  one-fourth  to  one  and  one-half 
inches  long  when  adult.  It  is  brown,  darker  than  the  German  roach, 
and  has  a  more  or  less  definite  yellow  band  around  the  margin  of  the 
pronotum  (Fig.  47).  It  is  a  native  of  the  warmer  parts  of  this  country 
but  has  spread  north  and  is  now  abundant  everywhere  except  in  the 
most  northerly  states. 

The  Australian  Roach  (Periplaneta  australasice  Fab.). — Somewhat 
smaller  and  apparently  broader  than  the  last,  and  with  the  yellow 
band  around  the  prothorax  brighter,  and  a  yellow  streak  on  the  costa 
of  the  fore  wing  extending  part  way  toward  the  tip  (Fig.  48).  It  is 
particularly  common  in  the  Southern  States. 

The  Oriental  Roach  (Blatta  orientalis  L.). — This  insect  is  the  " black- 
beetle"  of  Europe.  It  is  almost  black  and  the  wings  in  the  adult  male 
are  considerably  shorter  than  the  body,  while  in  the  female  they  are 
hardly  more  than  stubs.  It  is  a  stout-bodied  insect,  quite  generally 
present  in  the  eastern,  southern  and  central  United  States  as  far  west 
as  the  great  plains,  and  is  the  most  common  species  in  Europe  (Fig.  49). 

Other  kinds  of  roaches  are  occasionally  found  in  the  Northern  States 
brought  there  in  bunches  of  bananas  or  with  other  southern  fruits,  but 
they  do  not  appear  to  be  able  to  live  long  in  the  colder  climates. 

Control. — Various  materials  are  more  or  less  effective  as  roach  killers, 
but  the  best  of  these  is  commercial  sodium  fluorid.  It  may  be  mixed  with 
flour  or  some  other  inert  substance,  but  nothing  is  gained  by  this  except 
a  reduction  of  the  cost  of  treatment  and  the  killing  may  not  be  as  rapid. 
The  powder  is  thoroughly  dusted  where  the  roaches  occur,  particularly 
in  their  hiding  places,  using  a  dust  gun  or  blower.  The  insects  which 
by  crawling  or  in  other  ways  get  the  dust  on  their  antennae  or  legs,  clean 
these  parts  by  drawing  them  between  their  mouth  parts  so  that  the 
powder  enters  the  mouth  and  probably  acts  through  the  alimentary 
canal. 

Family  Mantidae   (The   Mantids) 

The  Mantids  are  usually  quite  large  insects  with  bodies  much  longer 
than  wide,  and  a  broad  head  which  moves  very  freely  upon  the  thorax. 
The  prothorax,  with  few  exceptions,  is  very  long,  and  bears  legs  adapted 
for  grasping  the  prey  and  which  are  well  provided  with  spines,  the  in- 
sects walking  on  the  other  four.  In  nearly  all  members  of  the  group 
the  wings  are  well  developed,  the  hinder  pair  larger  and  folding  in 
plaits  when  at  rest  with  the  other  pair  on  the  back  of  the  abdomen. 
They  are  often  called  Rear-horses,  Devil-horses,  Soothsayers,  Praying 
Mantids  or  Mule  Killers. 


THE  ORTHOPTEKA  79 

The  Mantids  are  carnivorous,  feeding  on  flies  and  other  insects  and 
are  therefore  beneficial.  Fifteen  to  twenty  kinds  occur  in  the  United 
States,  particularly  in  the  south,  but  the  group  is  mainly  found  in  tropical 
countries  where  it  reaches  its  greatest  development  and  includes  some 
remarkable  forms. 

Mantid  eggs  are  laid  in  cases  composed  of  a  thick  material  which 
quickly  dries.  They  are  usually  laid  in  the  fall  and  hatch  the  following 
spring.  Some  of  the  cases  are  very  noticeable,  being  an  inch  or  more 
long.  They  are  usually  attached  to  plant  stems  (see  Fig.  51). 


FIG.  50.  •  FIG.  51. 

FIG.  50. — Common  American  Mantis  (Stagomanlis  Carolina  L.)  waiting  for  its  prey. 
Slightly  reduced.     (Original.) 

FIG.  51. — Egg  case  of  common  American  Mantis,  natural  size.  (Original.) 

The  most  common  Mantis  (Stagomantis  Carolina  L.,  Fig.  50)  is  found 
as  far  north  as  southern  New  Jersey,  Pennsylvania  and  Ohio.  It  is  about 
two  and  one-half  inches  long  when  adult,  green  or  brown,  or  a  mixture 
of  the  two  colors,  and  is  found  not  only  on  plants  but  also  often  on 
houses,  sheds  or  in  other  places  where  it  may  obtain  its  prey.  It  locates 
in  some  spot,  then  raising  its  prothorax  and  head  somewhat,  with  its 
fore  legs. partly  extended,  quietly  waits  until  an  unwary  insect  comes 
within  its  reach.  When  this  happens,  a  quick  motion  of  its  fore  legs  and 
the  prey  is  seized,  the  spines  aiding  in  holding  the  insect,  which  is  then  fed 
upon. 

In  1897  a  Mantid  from  China  (Paratenodera  sinensis  Sauss.)  was  dis- 
covered near  Philadelphia  where  it  appears  to  have  successfully  estab- 
lished itself.  It  is  much  larger  than  the  common  native  Mantis,  being 
about  four  inches  long.  In  1899  the  common  European  Mantis  (Mantis 
religiosa  L.)  was  found  near  Rochester,  N.  Y.,  where  it  appears  to  be 
quite  common.  It  much  resembles  our  native  form  but  is  slightly  larger 
(Figs.  52  and  53). 


80 


APPLIED  ENTOMOLOGY 


As  these  insects  are  beneficial,  attempts  have  been  made  to  establish 
them  in  other  places,  but  thus  far  they  do  not  seem  able  to  withstand 
severe  winters,  and  in  the  case  of  the  last  named  species  it  has  until  now 


FIG.  52.  FIG.  53. 

FIG.  52. — European   Mantis   (Mantis  religiosa  L.),   natural  size,   with  wings  spread. 
(Original.) 

FIG.  53. — Egg  case  of  European  Mantis,  natural  size.      (Original.) 

apparently  been  unable  to  live  north  of  Ontario,  and  colonies  placed  in 
New  England  have  died  out. 

Family  Phasmidae    (The   Walking-Sticks) 

The  Phasmids  are  generally  called  "  walking-sticks."     Their  bodies 
are  usually  long  and  stick-like,  due  largely  to  their  very  long  and  slender 


FIG.  54. — Common  Walking-stick  (Diapheromera  femorata  Say)  natural  size.      (Original.) 

meso-  and  metathoracic  segments.     Their  legs  and  antennae  are  also 
generally  long,   and   the   15  to  20  kinds  found  in  the  United   States 


THE  ORTHOPTERA 


81 


are  wingless,  or  with  only  wing  stubs,  which  adds  to  their  stick-like 
appearance.  They  are  brown  or  green  in  color  and  thus  much  re- 
semble the  twigs  on  which  they  rest,  or  the  larger  leaf  veins.  Only 
one  species  (Diapheromera  femorata  Say)  is  abundant  except  in  the  more 
southern  states,  but  this  is  quite  generally  present  (Fig.  54). 

Walking-sticks  feed  on  foliage  and  when  abundant  may  entirely 
strip  many  acres  of  forest  trees  of  their  leaves,  though  this  does  not 
often  happen.  Their  eggs  are  laid  in  the  fall,  being  dropped  singly, 
wherever  the  insects  happen  to  be,  and  falling  to  the  ground  remain 
there  until  the  following  spring,  or  in  some  cases  until  the  second  spring, 
before  hatching.  Though  not  laid  a 
number  together  in  a  case  as  in  the  last 
two  families,  each  egg  has  a  case  or 
capsule  of  its  own. 

Where  forest  areas  are  attacked,  no 
entirely  satisfactory  method  of  control 
is  known.  In  the  case  of  a  few  trees  or 
plants  easily  accessible,  spraying  with  a 
stomach  poison  is  sufficient  to  prevent 
farther  injury. 

This  group  is  mainly  a  tropical  one, 
over  600  kinds  being  known,  very  variable 
in  size  and  appearance.  One  species  has 
a  body  nine  inches  or  more  in  length, 
and  with  its  front  legs  extended  forward 
and  its  hinder  ones  backward — a  position 
it  often  assumes — may  measure  sixteen 
inches  or  even  more,  while  its  body  has 
a  diameter  of  less  than  one-quarter  of 
an  inch.  In  the  tropical  forms  wings  are 
often  present,  and  in  some  cases  colored  and  marked  to  resemble  leaves. 
This  resemblance  is  increased  in  Pulchriphyllium  scythe  Gray  (Fig.  55) , 
found  in  the  East  Indies,  by  leaf -like  expansions  of  the  femora  and  tibiae 
and  of  the  body  itself. 

The  insects  belonging  to  the  three  families  of  this  order,  treated  thus 
far,  are  all  walkers  or  runners  (Cursoria).  Those  now  to  be  considered 
are  leaping  forms  (Saltatoria) ,  the  hind  legs  being  longer  than  the  others 
and  provided  with  powerful  muscles.  Their  heads  are  generally  strongly 
hypognathous,  the  mouth  being  directed  downward  and  in  some  cases 
even  a  little  backward.  Sounds  sometimes  called  musical  are  produced 
by  most  members  of  these  families. 

Family  Acrididse   (The  Grasshoppers) 

The  insects  belonging  in  this  group  are  commonly  called  grasshoppers. 
A  few  kinds  when  adult  migrate,  often  in  such  enormous  numbers  as  to 


FIG.  55. — A  Tropical  Leaf-insect 
(Pulchriphyllium  scythe  Gray)  about 
half  natural  size.  (Original.) 


82 


APPLIED  ENTOMOLOGY 


look  like  clouds  in  the  sky.  These  migrating  species  are  sometimes 
spoken  of  as  locusts. 

Grasshoppers  arc  feeders  on  grass  and  vegetation  in  general  and 
are  injurious,  the  amount  of  injury  they  cause  varying  with  their 
abundance.  Their  antennae,  shorter  than  the  body,  and  their  tarsi, 
consisting  of  only  three  segments,  quickly  distinguish  them  from  the 
related  family  Tettigoniidse.  The  pronotum  is  extended  backward 
somewhat,  and  down  on  the  sides  of  the  prothorax  almost  to  the  base 
of  the  fore  legs.  In  the  female  there  is  a  short,  stout  ovipositor  com- 
posed of  four  parts,  and  the  rather  narrow  fore  wings,  usually  somewhat 
leathery  in  texture,  cover  the  large,  delicate  hinder  pair  when  these, 
folded  in  plaits,  are  at  rest  above  and  along  the  sides  of  the  body. 

Most  grasshoppers  lay  their  eggs  in  the  ground,  usually  in  the  fall, 
and  these  hatch  the  following  spring.  The  female  works  its  ovipositor 
into  the  soil  a  short  distance,  then  pushes  apart  its  four  pieces  and 
deposits  its  eggs  in  a  cluster  containing  from  twenty-five  to  perhaps 


FIG.  56.  FIG.  57. 

FIG.  56. — Two-striped  Grasshopper  (Melanoplus  bivittatus  Say)  laying  eggs.  (Reduced 
from  U.  S.  D.  A.  Farm.  Bull.  747.) 

FIG.  57. — Sac,  or  "Egg-pod"  of  Grasshopper  eggs  in  the  ground.  About  natural 
size.  (Reduced  from  U.  S.  D.  A.  Farm.  Bull.  747.) 

five  times  that  number  of  eggs,  covered  by  a  fluid  which  hardens  and  forms 
a  sort  of  protecting  case  (Figs.  56  and  57).  The  young  on  hatching, 
work  their  way  out  of  the  ground  and  feed,  molting  several  times  and 
becoming  adult  after  2  or  3  months. 

Only  a  few  of  the  kinds  of  grasshoppers  found  in  the  United  States 
are  sufficiently  migratory  in  their  nature  to  deserve  the  name  "locust." 
During  the  period  between  1860  and  1880,  however,  and  to  some  extent 
since,  inhabitants  of  the  states  west  of  the  Mississippi  River  have  at 
times  suffered  the  entire,  or  almost  entire  loss  of  their  crops  by  the 
ravages  of  swarms  of  the  Rocky  Mountain  locust  (Melanoplus  spretus 
Thorn.)  which,  breeding  in  immense  numbers  on  the  eastern  slopes  of 
the  Rocky  Mountains,  upon  maturity  migrated  eastward  for  food,  and 
stripped  everything  where  they  alighted.  Settlement  of  these  breeding 
grounds,  and  cultivation,  destroying  the  eggs,  has  largely  put  an  end  to 
these  migratory  flights,  but  occasionally  grasshoppers  occur  in  destruc- 


THE  ORTHOPTERA 


83 


live  abundance,  not  only  in  the  West  but  in  all  parts  of  the  country 
wherever  they  become  so  plenty  as  to  lay  large  numbers  of  eggs  in  ground 
not  cultivated,  such  as  pastures.  Under  such  conditions,  a  sudden, 
more  or  less  local  outbreak  of  these  insects  may  take  place  in  the  spring, 
the  damage  being  caused  in  these  cases,  at  first  by  the  feeding  of  the 
nymphs,  and  later,  if  nothing  is  done,  by  the  adults. 

Aside  from  plowing,  harrowing  or  disking  land  in  which  grasshoppers 
breed,  before  the  eggs  hatch  in  the  spring,  the  most  successful  method 
of  control  when  they  appear  in  sufficient  abundance  to  make  treatment 
necessary,  is  the  use  of  a  poisoned  bait.  There  are  various  formulas  for 
this,  but  there  is  no  marked  difference  in  the  results  in  most  cases. 

One  in  general  use  is:  wheat  bran,  25  lb.;  Paris  green  or  white  arsenic, 

1  lb.;  oranges  or  lemons,  6  fruits  finely  chopped;  low-grade  molasses, 

2  qt.     Mix  the  bran  and  poison  well,  dry;  then  add  the  chopped  fruit 
and  its  juice;  finally  add  the  molasses  and  stir  thoroughly.     Enough 
water — 2  or  3  gal. — should  be  added  to  this  so  that  each  flake  of  the  bran 
is  sufficiently  moist  to  have  some  of  the  poison  adhere  to  it,  and  also 
take  up  the  flavor  of  the  fruit  and  molasses,  yet  not  enough  to  make 
the  flakes  stick  and  prevent  sowing  broadcast.     This  amount  of  material 
should  be  sufficient  to  spread  over  two  or  three  acres.     In  the  Eastern 
States  and  wherever  the  air  is  moist,  the  best  results  are  obtained  by 
spreading  the   bait   very   early  in   the   morning.     In  arid   or  semiarid 
regions,  3  or  4  gal.  of  water  may  be  needed  in  the.  mixture,  which  should 
be   distributed   toward   night. 

A  form  of  poisoned  bait,  known  as  the  modified  Griddle  Mixture, 
substitutes  a  half  barrel  of  fresh  horse  droppings  for  the  bran  and 
omits  the  molasses.  The  only  advantage  with  this  is  that  it  can  be  used 
where  bran  is  too  expensive  or  hard  to  obtain. 


FIG.  58.  FIG.  59. 

FIG.  58. — Red-legged  Grasshopper  (Melanoplus  fcmur-rubrum  De  G.)  about  natural 
size.  (Reduced  from  U.  S.  D.  A.  Farm. -Bull.  747  ) 

FIG.  59. — California  Devastating  Grasshopper  (Melanoplus  devastator  Scudd.)  about 
natural  size.  (Reduced  from  U.  S.  D.  A.  Farm.  Bull.  747.) 

There  are  many  kinds  of  grasshoppers  in  the  United  States.  Among  the 
more  abundant  and  therefore  injurious  species,  may  be  mentioned  the  red-legged 
grasshopper  (Melanoplus  femur-rubrum  De  G.,  Fig.  58),  about  an  inch  long,  its 
hind  tibiae  bright  red;  the  California  devastating  grasshopper  (Melanoplus 
devastator  Scudd.,  Fig.  59),  a  little  smaller,  found  in  the  Western  States;  the 
differential  grasshopper  (Melanoplus  differentiates  Thorn.),  about  an  inch  and  a 


84 


APPLIED  ENTOMOLOGY 


half  long,  present  nearly  everywhere,  but  rare  in  the  East;  the  two-striped 
grasshopper  (Melanoplus  bivittatus  Say)  about  the  size  of  the  last,  with  two 
yellow  stripes  along  its  back,  generally  distributed  except  in  the  South  Atlantic 
States  (Fig.  60);  the  lesser  migratory  grasshopper  (Melanoplus  atlanis  Riley) 
about  an  inch  long,  found  nearly  everywhere  in  the  United  States  and  frequently 


FIG.  60.  FIG.  61. 

FIG.  60. — Two-striped  Grasshopper  (Melanoplus  biviltatus  Say)  about  natural  size. 
(Reduced  from  U.  S.  D.  A.  Farm.  Bull.  747.) 

FIG.  61. — Lesser  Migratory  Grasshopper  (Melanoplus  atlanis  Riley)  about  natural 
size.  (Reduced  from  U.  S.  D.  A.  Farm.  Bull.  747.) 

seriously  abundant  west  of  the  Mississippi  River  (Fig.  61);  and  the  clear-winged 
grasshopper  (Camnula  pellucida  Scudd.)  which  though  small  is  often  very  injurious. 
It  is  found  in  all  the  northern  United  States  and  has  its  hind  wings  clear  and 
almost  colorless,  while  its  fore  wings  are  spotted  with  brown.  All  of  these 
species  attack  various  cereal  and  forage  crops. 


FIG.  62.— Florida   Lubber  Grasshopper  (Dictyophorus  reticulatus  Thunb.)   about  natural 
size.     (From  U.  S.  D.  A.  Farm.  Bull.  747.) 


In  the  Southern  and  Western  States  are  large,  short-winged  grasshoppers 
which  are  very  stout,  and  from  their  appearance  and  clumsy  movements  are 
called  "lubber  grasshoppers"  (Fig.  62).  They  attack  grass,  alfalfa  and  other 
crops. 

The  Carolina  grasshopper  (Dissosteira  Carolina  L.,  Fig.  63),  one  and  a  half 
inches  or  more  in  length,  is  gray  or  brown,  varying  somewhat  with  the  color  of 
the  ground  where  it  lives.  It  is  most  noticeable  along  roads  and  when  startled 
into  flight  its  black  hind  wings  with  yellow  margins,  and  the  crackling  sound 
often  produced  at  such  times  are  sufficient  to  attract  attention.  It  is  found 
throughout  the  entire  United  States, 


THE  ORTHOPTERA  85 

In  one  section  including  the  smallest  grasshoppers,  generally  called  "grouse 
locusts,"  some  of  which  are  less  than  half  an  inch  in  length,  the  pronotum  is 
extended  back  to,  or  even  beyond  the  end  of  the  abdomen  and  the  fore  wings 
are  reduced  to  mere  stubs.  Two  common  species  are  shown  in  Fig.  64. 

The  hind  wings  of  grasshoppers  are  often  brightly  colored,  yellow, 
red,  or  black.  The  legs  also  often  show  bright  colors. 


FIG.  63. — Carolina    Grasshopper    (Dissostvira    Carolina    Say)    natural    size.     (Original.) 

The  sounds  produced  by  grasshoppers  are  made  in  one  or  the  other 
of  two  ways.  In  some  species  the  hind  legs  are  drawn  up  and  down 
across  the  fore  wings,  ridges  on  the  inner  face  of  the  femur  scratching 
against  a  heavy  vein  on  the  wing  and  giving  a  rasping  sound.  In  others 
the  sound  is  produced  while  flying.  Here  the  front  edge  of  the  hind  wing 


FIG.  64. — Two  types  of  "Grouse  Locusts,"  natural  size.      (Original.) 

is  struck  against  the  under  surface  of  the  fore  wing,'  making  a  short, 
sharp  sound,  which,  quickly  repeated,  gives  a  kind  of  "crackling." 
Apparently  the  organs  of  hearing  are  located  on  each  side  of  the  body 
just  above 'the  base  of  the  hind  leg.  Each  is  a  rather  large,  smooth  disk, 
suggestive  of  an  ear  drum  membrane,  connected  by  nerve  fibers  with  a 
small  ganglion  which  in  turn  connects  with  the  main  nervous  system. 

Family  Tettigoniidae  (The  Green  Grasshoppers  and  Katydids) 

A  part  of  the  insects  of  this  family  are  called  green  grasshoppers, 
long-horned  grasshoppers,  or  meadow  grasshoppers,  while  others  are 
the  katydids.  Their  tarsi  consist  of  four  segments.  Most  of  them  are 
green  in  color,  and  all  have  antennae  longer  than  their  bodies.  Some  of 
the  katydids  have  broad  fore  wings  and  these  live  among  trees  and 
shrubs,  feeding  on  the  leaves  and  even  on  the  more  tender  twigs  (Fig.  65), 


86  .      APPLIED  ENTOMOLOGY 

Others  have  narrow  fore  wings  and  appear  to  prefer  bushes  or  tall  weeds 
and  grass  as  their  abiding  places  (Fig.  66).  The  meadow  grasshoppers 
resemble  the  narrow-winged  katydids  but  average  smaller  and  are  most 


FIG.  65.- — Broad-winged     Katydid     (Amblycorypha    rolundifolia    Scudd.),     natural    size. 

(Original.) 

abundant  in  fields  and  pastures,  particularly  where  the  grass  is  thick  and 
tall.  In  most  members  of  the  group  the  ovipositor  is  long  or  at  least 
large  enough  to  be  quite  noticeable. 


FIG.  66. —  Narrow-winged     Katydid     (Scudderia     curvicauda     De    G.),  slightly  enlarged. 

(Original.) 

Some  of  the  Tettigoniids  are  wingless  and  come  out  only  at  night, 
hiding  under  logs,  stones  or  in  dark  places  during  the  day.  They  are  of 
various  shades  of  brown  or  gray,  and  the  species  found  in  different  parts 
of  the  country  vary  much  in  appearance  (Fig.  67).  They  are  called 
" wingless  grasshoppers,"  "  camel  crickets,"  " shield-backed  grasshop- 


THE  ORTHOPTERA 


87 


pers,"  "  Jerusalem  crickets,"  etc.,  according  to  their  kind  and  the  local 
usage. 

Sound  in  this  family  is  produced  by  the  males.  The  base  of  the 
fore  wing  is  modified,  not  necessarily  in  the  same  way  in  all  the  species, 
but  in  such  a  manner  that  rubbing  these  wings  together  will  produce  a 
sound.  The  organ  of  hearing  is  a  small,  oval  membrane  located  near 


FIG.  67. — "  Wingless  Grasshopper,"  natural  size.      (Original.) 

the  base  of  the  tibia  on  each  side  of  the  front  leg.  Inside  the  membrane 
is  a  hollow  space  or  resonance  chamber,  and  a  nerve  supply.  The  sounds 
made  by  these  insects  are  produced  chiefly  toward  evening  and  at  night, 
though  in  dense  woods  they  may  sometimes  be  heard  earlier  in  the  day. 
The  members  of  this  group  are  rarely  serious  pests,  though  katydids 
have  been  known  to  injure  orange  groves  and  presumably  some  forest 


FIG.  68. — "Western    Cricket" 


(Anabrus   purpurascens    Uhl.),    slightly   enlarged. 
Gillette.) 


(After 


trees  suffer  more  than  is  generally  realized,  when  these  insects  are  abun- 
dant. One  exception  to  this  general  unimportance  of  the  family  is  met 
with  in  the  case  of  the  wingless  species  known  as  the  "western  cricket'' 
(Anabrus  purpurascens  Uhl.,  Fig.  68),  which  in  some  of  the  Western 
States  may  be  a  serious  crop  pest. 


88  APPLIED  ENTOMOLOGY 

Family   Gryllidse    (The   Crickets) 

The  crickets  are  familiar  insects,  often  seen  walking  or  leaping  over 
the  ground. 

In  this  family  the  wings  are  frequently  reduced  or  absent,  but  when 
present  the  front  pair  are  so  bent  that  one  part  lies  flat  over  the  back 
while  the  other  lies  against  the  side  of  the  body  when  not  in  use.  The 
antennae  are  in  most  cases,  longer  than  the  body.  A  convenient  group- 
ing of  these  insects  is  into  the  field  crickets,  the  mole  crickets  and  the 
tree  crickets. 


FIG.  69. — Common  Black  Cricket   (Gryllus  abbrevialus  Serv.),   natural  size.      (Original.) 

The  sounds  are  produced  by  the  wings  of  the  males,  which  are  rubbed 
over  each  other.  On  one  wing  is  a  strong  vein  which  bears  cross  ridges, 
while  on  the  other  is  a  thickened  area.  These  two  parts  (termed  file  and 
scraper  by  Comstock)  when  rubbed  together  cause  the  sound.  Ears  in 
crickets  are  located  as  in  the  last  family,  on  the  fore  legs,  but  the  two  on 
the  same  leg  differ  somewhat  in  appearance. 

The  common  field  crickets  (Fig.  69)  are  black  or  brown,  and  a  long 
ovipositor  is  present  in  the  females.  They  are  rather  indiscriminate 
feeders,  consuming  either  vegetable  or  animal  materials,  and  may  even 
be  cannibals.  In  houses  they  will  eat  foods  but  are  rarely  abundant 
enough  to  become  pests. 

The  mole  crickets  are  larger  and  stouter  than  the  common  field 
crickets,  and  because  of  their  habit  of  burrowing  in  the  ground  are  less 
often  seen  (Fig.  70).  They  are  brown  in  color  and  their  fore  legs  are 
broad  and  flat,  forming  most  effective  digging  organs.  The  eyes  are 
much  reduced  and  the  hind  legs  not  being  used  for  leaping,  are  not  so 
greatly  developed  as  in  the  other  crickets.  They  prefer  rather  moist 


THE  ORTHOPTERA 


89 


FIG.  70. — Common     Mole    Cricket    (Gryllotalpa    borealis    Burm.),    about    natural    size. 

(Original.) 


FIG.  71.  FIG.  72. 

FIG.  71. — Adult  Male  Tree  Cricket  ((Ecanthns  niveus  De  G.),  somewhat  enlarged. 
(Reduced  from  N.  Y.  Agr.  Exp.  Sta.  Tech.  Bull.  42.) 

FIG.  72. — Female  Tree  Cricket  ovipositing  in  a  twig.  Enlarged  about  one-half. 
(Reduced  from  N.  Y.  Agr.  Exp.  Sta.  Tech.  Bull.  42.) 


b  a 

FIG.  73. — Raspberry  canes  showing:  a,  row  of  egg  punctures  along  the  cane,  inducing 
cracking  open;  b,  cane  split  open  to  show  the  depth  of  the  punctures.  Natural  size. 
(Original.) 


90  APPLIED  ENTOMOLOGY 

land  in  which  to  make  their  burrows,  and  feed  on  plant  roots,  earth  worms 
and  insect  larvae.  The  "Changa"  (Scapteriscus  vicinus  Scudd.)  of  Porto 
Rico  attacks  the  roots  of  various  crops  in  that  island,  causing  much 
injury,  and  has  recently  been  discovered  along  the  sea  coast  of  some 
of  the  Southern  States  where  it  attacks  cotton  and  may  become  a  serious 
pest. 

The  tree  crickets  differ  greatly  in  appearance  from  the  field  and 
mole  crickets,  being  slender,  greenish  white  and  only  about  half  to  three- 
quarters  of  an  inch  in  length  (Fig.  71).  They  occur  on  trees  and  bushes 
and  attract  attention  from  July  till  .frost  by  their  shrill,  steadily  repeated 
note  or  song,  beginning  as  it  grows  dark  and  continued  through  the 
night,  the  rapidity  of  the  note  being  so  closely  related  to  the  temperature 
that  by  timing  the  number  of  repetitions  per  minute  a  close  approxima- 
tion to  the  thermometer  reading  can  be  obtained. 

The  tree  crickets  are  rather  serious  pests  as  during  the  fall  the  females 
make  long  rows  of  punctures  in  the  twigs  of  trees  and  in  berry  canes 
(Fig.  72),  laying  their  eggs  in  these  punctures  which  usually  are  nearly 
as  deep  as  the  diameter  of  the  twig  or  cane  (Fig.  73).  The  general 
result  is  the  drying  and  splitting  open  of  the  portion  of  the  plant  attacked, 
causing  its  death,  besides  providing  an  opportunity  for  the  spores  of 
fungous  diseases  to  enter  and  attack  the  plant.  Control  of  these  insects 
is  at  present  limited  to  cutting  off  and  destroying  the  injured  parts  of  the 
plant,  with  their  contained  eggs,  before  these  hatch  in  the  spring. 

A  few  species  of  crickets  live  a  semiparasitic  life  in  ants'  nests  and  in 
consequence  are  so  much  modified  as  to  show  little  resemblance  to  the 
common  forms. 


CHAPTER  XVII 
THE  ISOPTERA 

These  insects  are  commonly  called  White  Ants  or  Termites,  the 
former  name  being  used  because  though  not  nearly  related  to  ants, 
they  live  in  colonies  and  in  many  of  their  ways  .resemble  these  insects. 

The  White  Ants,  as  their  name  suggests,  are  whitish  in  color  (the 
winged  adults  may  be  brown  or  blackish).  The  group  is  essentially  a 
tropical  one  but  some  of  them  are  found  as  far  north  as  Canada.  The 


FIG.  74. — Castes  of  a  Termite  colony:  a,  queen;  b,  male;  c,  worker;  d,  soldier.      (After 
Jordan  and  Kellogg,  Evolution  and  Animal  Life,  D.  Appleton  and  Co.) 

tropical  species  differ  so  markedly  in  many  of  their  ways  from  the  north- 
ern ones  that  separate  descriptions  almost  seem  necessary.  In  all, 
however,  there  is  a  colonial  life  and  a  division  of  the  insects  into  several 
groups  or  "  castes." 

A  colony  normally  consists  of  one  or  more  males  or  " kings;"  one  or 
sometimes  several  females  or  " queens"  and  a  variable  but  generally 
large  number  of  other  individuals,  nearly  always  at  least,  of  two  castes, 
known  as  workers  and  soldiers  (Fig.  74).  These  may  be  individuals  of 
either  sex  which  have  not  developed  to  reproductive  maturity.  During 
a  short  period  of  their  lives  the  kings  and  queens  have  fully-developed 
wings,  four  in  number,  long,  narrow  and  quite  similar  in  appearance, 

91 


92 


APPLIED  ENTOMOLOGY 


which  when  at  rest  are  laid  flat  upon  the  back.  Near  the  base,  of  each 
wing  is  a  line  marking  where  it  will  easily  break  off.  The  part  between 
this  point  and  the  body  is  horny,  while  the  remainder  is  at  most  only 
somewhat  leathery.  At  the  end  of  the  abdomen  is  a  pair  of  short  cerci. 
Development  of  the  young  is  by  an  incomplete  metamorphosis. 

The  group  may  accordingly  be  characterized  as: 

Insects  living  in  colonies  and  of  several  castes,  of  which  only  the  kings 
and  queens  ever  have  wings.  These  are  four  in  number,  long,  more  or  less 
leathery,  narrow,  similar,  laid  flat  on  the  back  when  not  in  use,  and  easily 
broken  off  near  their  bases.  The  bodies  of  the  insects  are  soft,  and  usually 
whitish  in  color.  The  abdomen  has  a  pair  of  cerci  at  its  hinder  end.  Mouth 
parts  for  chewing.  The  metamorphosis  is  incomplete. 

The  food  of  Termites  is  mainly  dead  wood,  though  living  trees  and 
other  plants  sometimes  suffer  from  their  attacks.  Their  nests  in  the 
tropics  are  made  of  earth,  wood 
which  has  been  chewed  up,  and 
their  excrement.  They  are  often 
prominent  objects,  sometimes  twenty 


FIG.  76. 


FIG.  75. 

FIG.  75.  —  Adult  male  of  a  tropical  Termite  (Termes  spinosus  Latr.)  about  half  natural 
size.  (After  Desneux.) 

FIG.  76.  —  Laying  queen  of  a  tropical  Termite  (Termes  gilvus  Hag.).  Reduced  nearly 
one-half.  (From  Desneux.) 

feet  or  more  in  height,  and  seem  to  vary  in  form  to  some  extent  ac- 
cording to  the  species. 

Termites  "  swarm"  at  some  seasons,  enormous  numbers  of  winged 
kings  (Fig.  75)  and  queens  leaving  their  nest  at  about  the  same  time  and 
flying  off.  After  alighting  the  wings  are  broken  off  and  each  pair  of 
individuals  turns  its  attention  to  the  establishment  of  a  new  colony. 
In  the  tropical  species  which  form  large  nests  and  have  thousands  of 
individuals  in  a  colony,  the  abdomen  of  the  queen  gradually  becomes 
distended  by  the  developing  eggs  until  this  part  of  the  body  may  become 
several  inches  long  and  an  inch  or  more  in  diameter,  so  that  the  insect  is 
entirely  helpless  and  unable  to  move  (Fig.  76).  The  workers  which  are 
generally  blind,  provide  for  the  queen,  carry  away  the  eggs,  feed  and 
care  for  the  young,  construct  the  nest,  and  indeed  do  all  the  work  of  the 
colony.  The  soldiers  are  generally  regarded  as  a  caste  produced  for  the 


THE  ISOPTERA  93 

protection  of  the  colony,  but  numerous  observations  which  show  the 
workers  to  be  better  fighters,  throw  doubt  upon  the  real  duties  of  this 
caste. 

Other  castes  besides  those  already  mentioned  have  been  discovered 
in  different  species  of  Termites,  at  least  15  having  been  recognized,  though 
not  for  any  one  species.  In  addition  to  the  royal  pair,  workers  and 
soldiers,  however,  a  caste  consisting  of  individuals  generally  called 
complementary  kings  and  queens  or  neoteinic  members  of  the  colony 
is  generally  present,  at  least  in  the  older  colonies.  This  caste  is  capable 
of  reproduction,  though  less  abundantly  so  than  the  true  queen,  and 
appears  to  be  produced  to  continue  the  colony  after  her  death. 

The  most  generally  common  species  of  Termite  in  the  United  States 
(Reticulitermes  flavipes  Kol.)  except  perhaps  in  the  far  South  and  on  the 
Pacific  Coast,  does  not  appear  to  form  large  colonies  (see  Fig.  74).  Its 
nests  occur  under  logs  and  in  them,  in  fence  posts,  timbers  of  buildings 
or  other  structures,  or  in  tunnels  in  the  ground,  though  here  usually  in 
near  proximity  to  wood.  Centering  here  they  go  out  through  tunnels, 
always  protected  from  the  light,  mining  in  woodwork,  honeycombing 
it  and  leaving  only  a  thin  film  on  the  surface  to  conceal  them  and  shut 
out  the  light.  If  necessary  to  reach  the  wood  they  desire,  they  may 
construct  small  covered  passages  over  the  surface  of  stone,  brick  or 
similar  materials,  through  which  they  pass.  They  will  also  attack 
books  and  papers,  pasteboard,  leather,  etc.,  if  stored  in  dark  and  moist 
places.  In  some  cases  they  attack  trees,  infesting  roots  and  the  heart- 
wood  near  the  base.  Citrus  trees  in  the  South  are  often  seriously  in- 
jured by  them.  Field  crops  are  also  affected,  the  roots  being  fed  upon, 
and  plants  in  gardens  and  greenhouses  are  often  attacked,  the  termites 
sometimes  coming  up  to  the  benches  through  covered  tubes,  in  the  latter 
location,  and  working  first  in  the  wooden  bench  sides,  and  then  passing 
to  the  plants  themselves.  True  queens  have  seldom  been  found  in  the 
nests  of  this  species. 

Control. — To  check  the  ravages  of  these  insects  in  buildings,  bridges- 
and  other  structures,  all  infested  wood  should  be  removed.  Founda- 
tions should  be  of  stone,  brick  or  concrete,  and  as  far  as  possible  all 
timbers  should  be  exposed  to  light  and  not  be  so  placed  as  to  become  moist. 
As  these  insects  must  have  moisture  where  they  are,-dryness  is  an  effective 
protection.  Where  posts  must  be  set  in  the  ground  they  should  be  dipped 
in  coal-tar  creosote  before,  setting.  In  general,  ventilation  and  dryness 
should  be  secured  whenever  possible,  as  the  best  protection  against  the 
ravages  of  these  insects. 

The  Termites  are  not  a  large  group,  probably  numbering  less  than  two 
thousand  species,  but  the  size  of  their  nests  in  the  tropics  attracts  atten- 
tion, and  their  habits  and  colonial  life  are  of  much  interest.  They  appear 
to  be  most  closely  related  to  the  Orthoptera.  Fossil  species  are  quite 
numerous. 


94  APPLIED  ENTOMOLOGY 

About  1913  a  group  of  insects  was  discovered,  living  in  Ceylon,  Java, 
Africa  and  Costa  Rica,  which  seemed  to  differ  so  greatly  from  those 
already  known  as  to  justify  placing  them  in  a  new  order.  Those  first 
found  were  minute,  wingless,  with  only  vestiges  of  eyes  at  most,  and  a 
thorax  as  long  as  the  abdomen.  Cerci  are  present.  The  insects  aver- 
age about  a  twelfth  of  an  inch  in  length,  with  legs  similar  in  form  and 
used  for  running.  The  tarsus  consists  of  only  two  segments  and  the 
mandibles  are  well-developed,  the  mouth  parts  being  of  the  chewing 
type.  More  recent  discoveries  of  these  insects  in  Florida  and  Texas 
show  that  the  adult  females  may  have  well-developed  eyes;  wings,  at 
least  in  some  cases,  which  they  shed  like  the  Termites,  and  that  while  the 
head  resembles  that  of  the  Plecoptera  the  hinder  end  of  the  body  resem- 
bles that  of  the  Termites.  It  is  also  known  that  these  insects  are  social 
and  generally  occur  near  Termites,  though  not  usually  mingled  with 
them.  They  will  probably  prove  to  be  rather  nearly  related  to  the 
Isoptera. 

The  order  Zoraptera  has  been  established  to  include  these  insects, 
but  so  little  is  as  yet  known  about  them  that  they  have  not  been  treated 
in  a  separate  chapter  in  this  book. 


CHAPTER  XVIII 
THE  DERMAPTERA 

The  insects  belonging  in  this  group  are  commonly  called  Earwigs, 
because  of  a  mistaken  belief  that  they  crawl  into  the  ears  of  sleeping 
persons.  .They  are  most  abundant  in  warm  climates,  very  few  being 
found  in  the  more  northern  states.  Both  winged  and  wingless  species 
are  known,  the  wings  always  shorter  than  the  body  and  the  front  pair 
tough,  leathery  and  shorter  than  the  hinder  pair.  The  latter  are  very 
broad,  nearly  half-moon  shaped,  with  veins  radiating  from  a  point  behind 
the  costa  and  about  one-third  the  distance  from  the  base  to  the  apex. 
These  wings  first  fold  in  plaits  like  a  fan,  then  twice  across  to  reduce 
their  length  and  thus  bring  them  under  the  fore  wings,  the  forceps  aiding 
in  this.  At  the  end  of  the  abdomen  is  a  pair  of  prominent,  horny  cerci, 
shaped  like  forceps,  differing  in  form  in  the  two  sexes.  The  mouth  parts 
are  well  developed  and  of  the  chewing  type.  The  order  may  be  char- 
acterized as: 

Insects  which  when  adult  are  usually  rather  long  and  narrow  in  form; 
with  chewing  mouth  parts  and  a  pair  of  forceps-like  cerci  at  the  end  of  the 
abdomen.  Wings  may  be  absent  or  present:  in  the  latter  case  the  front 
wings  are  leathery  and  shorter  than  the  others  which  are  broad  and  fold  in 
plaits  from  a  center,  and  in  addition  fold  crosswise.  The  metamorphosis 
is  incomplete. 

Earwigs  are  not  generally  of  great  importance  as  pests  in  North 
America,  though  in  the  South  and  on  the  Pacific  Coast,  as  they  generally 
feed  on  fruits,  blossoms  and  other  vegetable  matter,  they  may  occasion- 
ally cause  some  injury.  This  appears  to  be  more  frequently  the  case  in 
Europe  than  in  this  country. 

They  hide  in  crevices,  among  leaves  and  in  the  ground  in  the  day  time, 
coming  out  at  night  to  feed.  In  the  northern  states  the  most  common 
species  is  the  Little  Earwig  (Labia  minor  L.),  brownish  in  color  and  only 
about  a  quarter  of  an  inch  long.  It  is  sometimes  attracted  to  lights  at 
night.  A  much  larger,  dark-brown,  wingless  species  (Anisolabis  mari- 
tima  Bon.),  a  native  of  Europe  has  now  reached  this  country  and  is 
found  on  the  sea  beaches  of  the  Eastern  United  States,  under  seaweed 
near  high-water  mark,  probably  feeding  chiefly  on  decomposing  vege- 
table matter  (Fig.  77). 

In  1911  the  common  European  Earwig  (Forficula  auricularia  L.), 
which  is  about  three-quarters  of  an  inch  in  length  when  adult,  was  found 

95 


96 


APPLIED  ENTOMOLOGY 


to  have  established  itself  at  Newport,  R.  L,  and  another  colony  of  this 
species  was  discovered  at  Seattle,  Wash,  in  1915  (Fig.  78).  Both  of  these 
colonies  are  increasing  and  spreading  rapidly.  The  adults  lay  their 
eggs  in  the  ground  in  the  fall  and  the  adult  females  winter  there  also. 


FIG.  77. — Adults  of  ;i  Wingless  Earwig  (Anisolabis  maritima  Bon.),  natural  size:  a,  male; 

b,  female.      (Original.) 

The  nymphs  feed  on  green  plant  shoots,  injuring  garden  plants  and  flowers 
during  the  spring,  and  later  in  the  season  turn  their  attention  to  blossoms, 
eating  the  stamens  and  bases  of  the  petals.  The  adults  too,  feed  on 
these  and  also  on  dead  flies,  larvae,  and  even  dead  or  dying  individuals 


FIG.   78. — Males  (a)  and  females  (6)  of  the  European  Earwig  (Forficula  auricularia  L.), 
about  twice  natural  size.      (From  U.  S.  D.  A.  Bull.  566.) 

of  their  own  kind.  Their  actual  injuries  however,  are  far  less  serious  than 
the  annoyance  caused  by  their  presence  in  residences,  where  they  crawl 
over  everything  at  night  and  hide  under  chair  cushions,  dishes,  in  folds 
of  clothing  and  in  all  crevices  in  and  about  the  houses  during  the  day. 


THE  DERMAPTERA  97 

Control. — During  the  spring  months  the  nymphs  may  be  destroyed 
by  the  use  of  poisoned  bread  bait,  using  16  Ib.  of  stale  bread  and  1  Ib.  of 
Paris  green  or  arsenic.  Grind  the  bread  fine  and  thoroughly  mix  it  with 
the  poison;  then  add  water  enough  to  make  a  mixture  which  will  run 
through  the  fingers  and  which,  spread  broadcast,  will  scatter  in  small 
particles.  Spread  this  during  the  evening  over  lawns  or  gardens  where 
the  insects  occur.  It  may  need  to  be  repeated  once  or  twice.  Afttr 
the  first  of  July  when  the  earwigs  have  taken  to  feeding  on  blossoms, 
th<j  best  treatment  thus  far  found  is  to  spray  the  plants  at  night  with 
the  following  contact  insecticide :  • 

Soft  potash  soap 30  oz. 

Water 96  oz. 

Nicotine  sulf ate  40  per  cent 20  teaspoonf uls 

Dissolve  the  soap  in  some  of  the  water  by  heating,  then  add  the  rest 
of  the  water  and  the  nicotine  sulfate,  making  about  a  gallon  of  stock 
solution.  For  use,  mix  1  part  of  this  with  22  parts  of  water.  The  spray 
should  be  a  fine  mist  and  be  thoroughly  applied,  to  be  effective. 

In  Europe  this  earwig  is  not  a  serious  pest,  perhaps  being  kept  in 
check  by  natural  enemies  not  present  in  this  country. 

The  Dermaptera  as  a  whole  cannot  be  considered  as  a  group  of  great 
economic  importance.  They  have  sometimes  been  regarded  as  a  family 
of  the  Orthoptera  and  sometimes  as  a  separate  order  akin  to  the  latter, 
but  recent  studies  seem  to  indicate  a  closer  relationship  to  the  Coleoptera 
or  beetles.  Probably  not  over  500  species  of  the  group  are  known. 


CHAPTER  XIX 
THE  COLEOPTERA 

The  Coleoptera  or  beetles  is  the  largest  group  of  insects  and  members 
of  it  are  familiar  to  everyone.  Over  175,000  kinds  are  already  known, 
and  more  are  discovered  every  year.  Beetles  usually  have  wings,  though 
in  some  cases  they  are  very  small  and  never  used.  The  front  pair  are 
hard  and  horny  and  are  called  elytra.  They  are  not  used  in  flight  but 
when  closed  lie  flat  on  the  back,  covering  and  protecting  the  hind  wings 
and  the  rather  soft  external  skeleton  of  the  upper  side  of  the  abdomen. 


FIG.  79. — Water  Beetle  with  wings  spread.      (From  Folsom.} 

In  some  groups  they  do  not  reach  the  end  of  the  body,  and  in  those  in- 
sects the  unprotected  portion  of  the  abdomen  is  generally  of  its  usual 
thickness.  The  hind  wings  are  usually  quite  large  and  fold  in  an  irregular 
peculiar  way  to  reduce  their  size  and  bring  them  under  the  elytra  when 
they  are  not  in  use  (Fig.  79). 

The  external  skeleton  of  the  beetles  is  usually  harder  and  thicker 
than  in  most  of  the  other  groups.  The  mouth  parts  are  for  chewing, 
both  as  larvae  and  adults,  and  the  jaws  are  often  very  powerful.  The 
early  stages  are  entirely  unlike  the  adult  condition,  the  members  of  this 
group  undergoing  a  complete  metamorphosis. 

98 


THE  COLEOPTERA  99 

The  distinctive  characters  of  the  group  are: 

Insects  which  as  adults  nearly  always  have  four  wings,  the  front  pair 
entirely  thickened  and  horny;  the  hind  pair  membranous:  mouth  parts  for 
chewing:  body  usually  rather  stout.  Metamorphosis  complete. 

There  is  a  great  diversity  in  the  structure  of  the  antennae  in  different 
beetles,  and  also  in  the  form  of  the  legs  and  number  of  tarsal  segments. 
The  arrangement  of  the  skeletal  plates  around  the  articulation  of  the 
fore  coxae  to  the  body  is  also  variable  and  of  importance  in  classification. 

Eggs  of  the  Coleoptera  are  laid  in  many  kinds  of  places — on  leaves, 
in  branches,  in  decaying  matter,  water,  etc.  The  larvae  which  hatch 
are  usually  called  " grubs"  except  when  they  bore  in  wood.  Then,  as 
with  larvae  of  any  order  found  under  such  conditions,  they  are  termed 
"  borers."  They  usually  have  the  three  pairs  of  legs  which  become  those 
of  the  adult,  though  these  are  sometimes  wanting.  Some  feed  upon  other 
animals,  some  on  leaves  or  wood,  some  on  carrion,  and  others  on  various 
substances.  After  full  larval  growth  has  been  attained  they  pupate. 
The  pupal  shell  or  skeleton  generally  covers  the  surface  of  the  body 
closely,  but  the  wings  and  legs  though  lying  close  to  it  are  covered  sepa- 
rately as  projecting  appendages  and  not  ensheathed  by  the  shell  enclosing 
the  body  proper.  Such  a  pupa  case  is  called  a  pupa  libera,  or  free  pupa. 
In  some  Coleoptera  this  condition  does  not  obtain,  the  pupa  shell  en- 
closing wings,  limbs  and  body  with  no  projecting  appendage  sheaths, 
and  such  a  case  is  called  a  pupa  obtecta  (see  Fig.  33). 

The  beetles  are  generally  divided  as  a  matter  of  convenience  into  the 
true  Coleoptera  (Coleoptera  genuina  or  Coleoptera  vera)  and  the  Snout 
Beetles  (Rhynchophora),  though  it  is  at  least  doubtful  if  the  latter  is  a 
natural  group.  The  insects  in  this  section  are  easily  recognized,  in  most 
cases,  by  having  the  front  of  the  head  prolonged  into  a  snout  which  may. 
be  long  and  slender — in  some  cases  even  longer  than  the  body — or  short 
and  stout,  being  sometimes  so  short  as  to  be  hardly  noticeable.  The 
antennae  arise  from  the  sides  of  the  snout  and  in  most  cases  have  a  .bend 
like  an  elbow  near  the  middle.  The  mouth  parts  are  at  the  end  of  the 
snout,  but  the  labrum  and  both  pairs  of  palpi  are  absent.  The  insects 
of  this  group  are  even  more  firm  bodied  than  the  other  Coleoptera. 

The  true  beetles  (Coleoptera  vera)  have  no  snout.  The  mouth  parts 
are  all  present  and  as  a  group  its  members  average  larger  than  the 
Rhynchophora:  indeed  the  largest  bodied  insects  known  belong  here. 

THE  TRUE  COLEOPTERA  (Coleoptera  vera) 

This  is  by  far  the  larger  section  of  the  beetles,  more  than  75  of  the 
80  odd  families  belonging  here.  They  vary  greatly  in  structure,  habits 
and  food.  Many  of  the  families  are  of  little  or  no  economic  importance 
and  have  few  members,  while  others  include  a  very  large  number  of 
species,  many  of  wnich  are  very  destructive. 


100 


APPLIED  ENTOMOLOGY 


Family  Lampyridae  (Fire  flies,  etc.). — In  several  ways  the  insects 
belonging  here  appear  to  be  among  the  simplest  of  the  beetles  (Fig.  80). 
Their  bodies  are  quite  soft  as  compared  with  the  others;  the  abdomen  has 
been  little  reduced,  seven  or  eight  segments  being  perceptible,  and  the 
larvae  are  quite  simple  and  feed  on  small  insects  and  other  animals  such  as 
snails,  either  living  or  dead. 

Only  a  few  members  of  the  group  are  often  noticed  except  by  ento- 
mologists, but  those  which  attract  attention  are  familiar  by  the  light  they 

produce  at  night,  which  has  given  them  the 
names  "fire  flies,"  "lightning  bugs,"  etc.  The 
light  is  produced  by  specialized  areas  of  the 
body,  frequently  at  least  on  the  underside  of 
the  abdomen  near  its  tip.  The  light  itself  is 
not  persistent  but  comes  in  flashes  and  is  dis- 
tinctly yellow  in  most  cases.  It  is  believed  to 
be  produced  by  the  oxidation  of  granules  in  the 
outer  layer  of  the  luminous  organ,  the  oxygen 
being  supplied  by  the  tracheae,  and  under 
control  of  the  nervous  system.  In  some  species  the  adult  female  is 
wingless  so  that  its  light  appears  as  it  crawls  on  the  ground,  and  such 
individuals  are  often  called  "glow-worms." 

Other  insects  and  animals  also  have  luminous  organs,  but  the  lights 
they  produce  are  probably  less  frequently  seen  than  those  made  by  Lam- 
pyrids,  these  being  widely  distributed  and  very  abundant  insects. 


FIG.  80. — Examples  of 
Common  Lampyrid  Beetles, 
about  natural  size. 

(Original.) 


FIG.  81. — Common  Ground  Beetle 
(Harpalus  caliginosus  Fab.),  natural 
size.  (Original.} 


FIG.  82 .  —  European  Calosoma  Beetle 
(Calosoma  sycophanta  L.)  and  its  larva,  natural 
size.  (Original.) 


Family  Carabidae  (Ground-beetles). — These  insects  are  active,  running  quickly 
over  the  ground,  and  the  group  is  a  large  one  containing  many  different  species, 
over  1,200  of  which  are  found  in  the  United  States  (Fig.  81).  They  feed  mainly 
at  night,  hiding  by  day,  and  the  majority  are  dark  colored  or  black,  though  a  few 
have  bright  colors.  They  are  predaceous,  both  as  larvaB  and  adults  in  most 
cases,  though  a  few  have  been  known  to  depart  from  their  usual  habits  and  feed  on 
berries  and  seeds.  One  species  (Calosoma  sycophanta  L.)  has  been  brought  to  this 
country  from  Europe  as  it  feeds  to  quite  an  extent  on  the  caterpillars  of  the  Gypsy 


THE  COLEOPTERA 


101 


Moth,  even  climbing  trees  in  search  of  its  prey,  and  it  is  now  fairly  common  in 
most  of  the  New  England  States  (Fig.  82).  Asa  whole,  the  group  is  distinctly  a 
beneficial  one,  feeding  on  injurious  insects  both  above  ground  and  as  these  enter 
the  ground  to  pupate. 

Family  Cicindelidae  (Tiger  beetles). — The  active  flight  and  bright  colors 
of  many  of  the  tiger  beetles,  though  most  of  them  are  small  insects,  only  about 
half  an  inch  long,  make  the  members  of  this  family  quite  noticeable  (Fig.  83). 
They  are  sun- loving  forms,  most  common  along  roadsides  and  in  sandy  places. 
When  flushed  they  fly  quickly  a  few  yards,  then  alight  and  often  turn,  facing  the 
intruder  as  though  watching  his  movements.  Both  they  and  their  larvae  feed  on 
other  insects,  the  larva  living  in  a  burrow  in  the  ground  and  placing  itself  at  the 
mouth  of  the  burrow  ready  to  grasp  any  unwary  insect  which  may  come  near. 
The  elytra  of  the  adult  are  usually  metallic  brown  with  light-colored  marks  sug- 
gestive of  musical  characters  or  perhaps  hieroglyphics,  though  in  some  cases  bright 
green,  purple,  or  other  colors  dominate.  In  the  West  the  largest  insect  belonging 
to  this  family  (Amblychila  cylindriformis  Say)  does  its  hunting  at  night,  as  is  also 
the  case  with  certain  related  forms  of  the  Pacific  Coast. 


FIG.  83.— Tiger  Beetle  (Cicindela),  slightly 
enlarged.     (Original.) 


"FiG.  84. — Dytiscid  Beetle  (Dytisciis  verticalis 
Say),  natural  .size.     (Original.) 


Family  Dytiscidae  (Carnivorous  diving-beetles). — Members  of  this  family  are 
present  in  almost  every  quiet  stream  and  pond.  They  are  oval,  rather  flat 
beetles,  usually  black,  and  good  swimmers,  the  hinder  pair  of  legs  being  broad  and 
somewhat  oar-like  and  heavily  fringed  with  hairs  (Fig.  84).  The  antennae  are 
thread-like.  Whenever  they  need  air,  they  float  up  to  the  surface  of  the  water 
and  allow  the  hinder  end  of  the  body  to  project  a  little  out  of  the  water.  Then, 
lifting  the  elytra  slightly,  the  air  enters  the  space  under  them  and  is  retained 
there  aided  by  hairs  present.  The  insect  can  now  stay  under  water  until  this  air 
supply  has  been  exhausted.  The  larvae,  often  called  "water-tigers, "  they  are  such 
voracious  creatures,  feed,  like  the  adults,  on  various  water  insects  and  other 
animals,  even  attacking  small  fish.  Some  of  this  family  may  be  at  least  an  inch 
and  a  half  long. 

Family  Gyrinidae  (Whirligig-beetles). — These  insects  swim  on  the  surface 
of  quiet  water,  generally  in  groups,  and  go  around  and  around  in  a  "whirligig" 
sort  of  fashion.  They  are  usually  bluish-black,  oval  in  form,  and  the  compound 


102 


APPLIED  ENTOMOLOGY 


eyes  are  so  divided  that  one  part  of  each  is  directed  upward  and  the  other  down- 
ward (Fig.  85).  They  feed  on  small  insects  which  come  within  their  reach.  The 
larvae,  living  in  the  water,  breathe  by  abdominal  tracheal  gills,  and  are  also 
carnivorous.  The  group  does  not  include  many  species,  but  their  habit  of 
swimming  in  companies,  and  their  peculiar  " gyrating"  over  the  surface  attracts 
attention,  nearly  everybody  having  noticed  them  on  this  account. 

Family  Hydrophilidae  (Water-scavenger  beetles). — The  water-scavenger 
beetles  occur  in  the  same  types  of  stream  and  pond  as  the  carnivorous  diving 
beetles,  which  they  greatly  resemble  (Fig.  86).  The  outline,  however,  is  usually 
a  little  more  elongately  oval;  the  antennae  are  club-shaped,  and  in  addition  to 
other  structural  differences,  they  obtain  air  by  raising  the  head  slightly  above 


FIG.  85.  FIG.  86.  FIG.  87. 

FIG.  85. — Gyrinicl  or  Whirligig  Beetle  (Dineutes),  natural  size.      (Original.) 
FIG.  86. — Water-scavenger  Beetle  (Hydrous  triangularis  Say),  natural  size.     (Original.) 
FIG.  87. — Rove-beetle   (Staphylinus  vulpinus  Nordm.),  slightly  enlarged.     (Original.) 


the  surface  and  collecting  a  film  of  it  over  the  under  surface  of  the  body,  where 
it  is  retained  by  a  close  coating  (pubescence)  of  fine  hairs.  They  feed  on  decay- 
ing animal  and  plant  material  for  the  most  part,  though  sometimes  taking  to 
living  plants  and  insects.  Some  species  may  be  about  two  inches  in  length. 
They  are  of  little  economic  importance. 

Family  Staphylinidae  (Rove-beetles). — This  large  family  in  some  regards  is 
suggestive  of  the  fire  flies  as  the  body  of  the  insect  in  this  group  is  not  as  hard 
and  firm  as  in  most  beetles  and  seven  or  eight  abdominal  segments  are  present 
(Fig.  87).  In  other  ways,  however,  it  differs  greatly  from  the  Lampyrids,  the 
body  being  slender  for  its  length,  and  the  elytra  short,  not  nearly  covering  the 
top  of  the  abdomen,  the  segments  of  which  are  very  movable.  The  insects  run 
rapidly,  often  lifting  up  the  end  of  the  abdomen  in  a  menacing  way.  Most  of 
the  thousand  or  more  species  found  in  this  country  are  small,  the  larger  kinds 
seldom  being  more  than  an  inch  long.  They  are  land  forms,  feeding  on  decay- 
ing vegetable  and  animal  materials  near  which,  or  under  stones  and  wood, 
they  are  found.  They  must  be  considered  as  beneficial  insects,  acting  as  scav- 
engers. 


THE  COLEOPTERA 


103 


Family  Silphidae  (Carrion-beetles). — Most  of  the  members  of  this  family 
are  of  good  size,  ranging  from  half  an  inch  to  three  times  that  length.  Two 
rather  distinct  types  of  insect  are  common  in  the  group,  one  (Silpha,  Fig.  88) 
having  a  broad,  rather  flat  body  and  with  the  sides  of  the  prothorax  very  thin. 
These  insects  average  less  than  an  inch  in  length  and  the  elytra  are  usually 
black.  In  the  other  type  (Necrophorus,  Fig.  89)  the  insect  is  larger,  stout,  with 
a  body  more  cylindrical,  and  the  elytra  generally  have  dull  red  markings  and 
are  frequently  shorter  than  the  abdomen.  Both  types  feed  on  dead  animals  in 
most  cases,  and  their  larvae  have  the  same  food,  so  that  the  group  may  therefore 
be  regarded  as  beneficial.  It  is  not  a  very  large  family,  in  the  United  States 
at  least. 


FIG.  88.  —  Carrion-beetle  (Silpha 
americana  L.),  about  natural  size. 
(Original.) 


FIG.  89. — Carrion-beetle  (Necrophorus 
marginatus  Fab.),  slightly  enlarged. 
(Original.) 


Family  Dermestidae  (Dermestids). — These  insects  are  small,  the  largest 
common  species  in  this  country  being  only  about  one-third  of  an  inch  long.  Most 
of  them  are  rather  short,  thick-set  beetles,  covered  with  very  small  scales  which 
give  them  a  gray  or  brown  color,  with  occasional  black,  white  or  red  scaly  areas 
in  some  cases,  prodwing  spots  or  bands  of  these  colors.  They  feed  on  decaying 
substances,  but  those  most  important  as  pests  attack  wool,  furs,  feathers  and 
meat,  cheese  and  fats.  In  some  cases  the  adults  feed  on  pollen  and  only  the  larvae 
are  destructive. 

The  Larder  Beetle  (Dermestes  lardarius  L.). — This  common  insert  is  fre- 
quently found  in  pantries  on  foods,  particularly  of  a  fatty  nature.  The  adult 
(Fig.  90)  is  dark  brown,  with  a  pale-yellowish  band  across  tha  elytra  near  their 
bases,  in  which  are  a  few  black  dots.  The  larva  (Fig.  91)  is  longer  and  more 
slender  than  the  adult,  with  numerous,  rather  long,  black  hairs;  is  brown  in 
color,  and  attacks  ham,  cheese,  beeswax,  feathers,  and  almost  any  material  oily 
or  fatty  in  its  nature. 

Control. — Little  can  be  done  in  the  way  of  controlling  this  pest,  except  by- 
cleanliness  and  close  watch  of  all  fatty  substances  kept  in  stock,  removing  and 
destroying  the  insects  whenever  they  are  discovered.  Tightly  closed  receptacles, 
giving  no  opportunity  for  the  insects  to  enter,  should  be  used  in  which  to 
keep  such  substances. 


104  APPLIED  ENTOMOLOGY 

The  Buffalo  Carpet  Beetle  (Anthrenus  scrophularm  L.). — The  adult  of  this 
insect  is  a  tiny  beetle  about  three-sixteenths  of  an  inch  long,  mottled  black  and 
white,  with  a  red  line  having  three  pairs  of  side  branches  or  lobes,  down  the  middle 
of  its  back  (Fig.  92).  It  is  a  household  pest  in  the  northeastern  states  and  as 
far  west  as  Iowa  and  Kansas.  In  Europe,  of  which  country  it  is  a  native,  it 
does  not  appear  to  be  of  much  importance.  The  beetles  appear  in  the  fall  and 
may  continue  to  be  found  in  heated  houses  all  winter.  The  eggs  are  laid  on 
woolen  cloth  or  clothes,  carpets,  rugs,  furs,  feathers  or  silk,  all  of  these  being 
animal  products,  and  the  small  hairy  larvsB  feed  on  the  materials  named.  After 
pupation  has  been  completed,  the  adults  appear  and  are  often  noticed  on  windows. 
In  the  spring  months,  probably  after  laying  their  eggs,  the  beetles  appear  out- 
of-doors  and  feed  on  the  pollen  of  various  blossoms,  the  Spircea  being  a  favorite. 


FIG.  90.  FIG.  91.  FIG.  92. 

FIG.  90. — Adult  Larder  Beetle  (Dermestes  lardarius  L.)  four  times  natural  size.  (From 
Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan  Company, 
Publishers.) 

FIG.  91. — Larva  of  the  Larder  Beetle,  three  times  natural  size.  (From  Herrick's 
Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan  Company,  Publishers.) 

FIG.  92. — Adult  Buffalo  Carpet  Beetle  (Anthrenus  scrophularioe  L.),  nine  times  natural 
size.  (From  Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan 
Company,  Publishers.) 

Whether  there  is  more  than  one  generation  a  season  has  not  been  definitely 
settled.  Many  of  the  larva?  breed  in  floor  cracks  under  carpets  and  rugs,  on  the 
woolen  debris  there. 

A  somewhat  similar,  closely  related  beetle,  the  Black  Carpet  Beetle  (Attagenus 
piceus  Oliv.),  also  of  European  origin,  and  dull  black  in  color  (Fig.  93),  is  likewise 
an  enemy  to  the  same  general  class  of  materials  as  the  Buffalo  Carpet  Beetle. 
It  appears  to  be  a  pest  farther  south  than  the  last-named  insect.  The  larva 
(Fig.  94)  is  longer  and  more  slender  than  that  of  the  Buffalo  Carpet  Beetle,  reddish- 
•  brown,  and  with  a  tuft  of  long  hairs  at  the  end  of  its  body. 

Control  of  Carpet  Beetles. — These  insects  are  repelled  by  the  odors  of  various 
substances,  and  clothing,  furs,  feathers,  etc.,  when  put  away,  can  be  protected 
from  their  attacks  by  placing  them  in  tight  bags  or  boxes,  together  with  the  repel- 
lent. Naphthaline  ("moth  balls")  is  the  most  effective  for  this  purpose,  and 


THE  COLEOPTERA  105 

the  oil  in  cedar  wood  is  also  of  value,  hence  the  use  of  cedar  chests  for  storage 
purposes,  these  giving  some  protection  as  long  as  their  odor  lasts.  Camphor  also 
is  a  fair  repellent.  But  with  all  these  materials  the  tendency  is  to  use  too  little, 
and  in  such  cases  the  insects  are  not  driven  off.  Then  too,  if  the  food  of  these  pests 
be  put  away  with  either  eggs  or  larvae  present,  the  repellent  will  not  prevent  the 
larvae  from  feeding.  The  best  practice  therefore,  is  to  fumigate  all  material 
likely  to  be  attacked,  before  packing  it  away,  placing  it  in  a  tight  box  and  treating 
it  with  Carbon  disulfid  for  24  hr.  Then  add  a  liberal  supply  of  moth  balls  and 
close  tightly.  The  fumingation  will  destroy  these  pests  in  any  stage  in  which 


FIG.  93.  FIG.  94. 

FIG.  93. — Adult  Black  Carpet  Beetle  (Attagenus  piceus  Oliv.),  enlarged  nine  times. 
(From  Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan 
Company,  Publishers.) 

FIG.  94. — Larva  of  the  Black  Carpet  Beetle,  five  times  natural  size.  (From 
Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan  Company", 
Publishers.) 

they  may  be  present,  while  the  naphthaline  will  keep  out  adults  which  might 
otherwise  enter  thereafter.  Fumigation  of  a  room  or  an  entire  house  if  necessary, 
with  Hydrocyanic  acid  gas,  or  sulfur,  is  also  a  good  treatment,  though  if  the  latter 
substance  be  used  its  effect  upon  metals,  and  on  colors  in  clothes  and  wallpapers 
should  be  remembered.  Carpets  may  be  steam-cleaned,  this  killing  the  pest  in  all 
stages,  and  cold  storage  for  furs  and  feathers  at  least,  if  the  temperature  be  kept 
below  40°F.  will  prevent  injury,  though  not  necessarily  killing  any  of  the  insects 
which  may  be  present.  As  some  of  the  larvae  may  be  in  floor  cracks  when  carpets 
and  rugs  are  infested,  these  should  be  treated  with  kerosene  or  gasoline.  Woolen 
clothing  kept  in  closets  during  the  warmer  seasons  of  the  year  should  be  frequently 
brushed  out  and  aired  in  the  sunlight. 

Family  Buprestidae  (Flat-headed  Borers). — This  group  of  beetles 
contains  many  forms  which  injure  trees  by  boring  in  their  trunks. 
Others  attack  berry  canes  which  often  show  swellings  as  a  result.  A 
few  are  leaf  miners  or  gall  makers.  The  adults  are  generally  stout, 
robust  beetles  with  heads  set  into  the  thorax,  rather  flat  backs,  and  in 
general  dark  colored  but  with  a  metallic  luster,  though  a  few  are  bright 


106 


APPLIED  ENTOMOLOGY 


green  or  other  colors.  The  larvae  which  bore  in  trees,  are  white  except 
for  a  small,  yellowish  head,  and  have  a  large,  flattened  prothorax  and  no 
legs.  Some  of  these  insects  attack  pines;  others,  different  forest  trees, 
burrowing  at  first  just  under  the  bark  in  the  sap-wood  and  later  in  the 
heart-wood.  The  average  life  history  requires  about  a  year  for  its  com- 
pletion, but  if  the  tree  be  vigorous  the  larva  is  liable  either  to  die  or  be 
delayed  in  its  development.  The  adults  are  fond  of  the  sun  and  fly 
freely  in  the  daytime.  They  are  often  found  on  flowers.  Several  hun- 
dred species  are  known  in  this  country,  all  of  them  injurious,  the  damage 
they  do  being  largely  dependent  upon  the  importance  of  the  tree  or 
plant  they  attack. 

The  Flat-headed  Apple-tree  Borer  (Chrysobothris  femorata  Fab.). — 
This  is  probably  the  most  injurious  of  the  Buprestids.  It  attacks  more 
than  30  kinds  of  trees  and  shrubs,  generally  selecting  individuals  which 
are  not  in  a  healthy  condition  or  are  otherwise  favorable  for  their  larvae. 


FIG.  95. — Adult  Flat-headed   Apple-tree   Borer   (Chrysobothris  femorata   Fab.),   enlarged 
3>4  times.     (From  U.  S.  D.  A.  Farm.  Bull.  1065.) 


The  beetle  (Fig.  95)  is  about  half  an  inch  long,  rather  broad,  dark  brown, 
faintly  marked  with  bands  and  indefinite  spots  of  gray,  and  having  a 
brassy  metallic  reflection  at  certain  angles.  The  underside  is  bronze, 
and  under  the  wings  the  abdomen  is  a  metallic  greenish-blue.  It  occurs 
almost  everywhere  in  the  United  States  and  in  Southern  Canada,  and 
is  a  serious  enemy  of  fruit  trees. 

The  beetles  appear  soon  after  apple-blossom  time  and  live  for  several 
weeks.  They  frequent  the  sunny  side  of  the  trunks  and  limbs  of  trees. 
Here  the  eggs  are  laid  in  fine  cracks  or  under  small  scales  of  the  bark. 
They  hatch  in  from  2  to  3  weeks  and  the  tiny  larva  (Fig.  96)  bores  into 
the  inner  bark,  feeding  on  this  and  on  the  sap-wood  and  grows  rapidly 


THE  COLEOPTERA 


107 


unless  the  tree  is  vigorous,  in  which  case  such  an  outpouring  of  sap  may 
occur  at  the  wound  as  to  kill  (drown?)  it  or  drive  it  into  the  outer  layers 
of  bark  where  it  may  live  for  a  time,  later  working  back  into  the  sap-wood 
if  the  flow  becomes  small  enough  to  permit  it.  If  the  larva  can  feed  in 
the  sap-wood  it  will  grow  to  full  size,  about  an  inch  long,  by  fall,  at  this 
time  burrowing  into  the  wood  to  form  a  pupal  cavity  in  which  the  winter 
is  spent,  pupation  itself  taking  place  there  the  following  spring  and  con- 
tinuing several  (throe  to  four)  weeks,  after  which  the  adult  beetle  escapes. 


FIG.  96. — Flat-headed  Apple-tree  Borers  (lance)  of  various  sizes.     Natural  size.     (From 
U.  S.  D.  A.  Farm.  Bull.  1065.) 

Control. — Vigorous,  healthy  trees  are  not  generally  liable  to  attack, 
and  cultural  methods  which  will  insure  this  condition  are  important. 
Trees  headed  low  will  shade  their  trunks  and  the  sun-loving  beetles  will 
go  to  those  exposed  to  sunlight.  Shading  trunks  exposed  to  the  sunlight, 
by  boards  cutting  off  this  light,  is  a  protection,  as  are  also  poles  set  in 
the  orchard  and  covered  with  sticky  material  to  catch  and  hold  the  beetles 
visiting  them  in  search  of  places  to  lay  their  eggs.  Wrappings  of  burlap 
or  paper  extending  from  the  ground  to  the  limbs  will  prevent  egg-laying, 
but  should  be  removed  when  this  period  is  past.  Birds  and  insect  enemies 
aid  in  controlling  this  pest. 

Family  Elateridae  (Snapping  beetles;  click-beetles;  skip-jacks). — 
These  insects  somewhat  resemble  the  Buprestids  when  adult  but  are 
usually  more  slender,  with  their  sides  more  nearly  parallel,  and  the 
economic  species  also  lack  a  metallic  reflection.  The  hinder  corners  of 
the  pronotum  are  elongated  forming  sharp  points  in  the  majority  of  the 
.  group,  and  the  insects  are  usually  some  shade  of  brown  or  blackf  though 
the  pronotum  and  elytra  sometimes  differ  in  color  and  the  latter  are 
spotted  in  some  cases,  mottled  black  and  white  in  our  largest  common 
species,  and  some  have  rather  bright  colors  or  markings  (Figs.  97  and  98). 
When  these  insects  fall  on  their  backs  they  are  able  to  throw  themselves 


108 


APPLIED  ENTOMOLOGY 


into  the  air  by  a  sudden  snap  of  the  body  for  the  purpose  of  getting  onto 
their  feet  as  they  alight  again,  and  if  this  fails  at  first  the  snapping  is 
repeated.  The  larvae  (Figs.  97  and  98),  commonly  called  wireworms, 
are  nearly  all  slender,  yellow  or  brown,  with  very  hard  shells,  often  glis- 
tening, one  sub-family  where  they  are  soft-bodied  and  white  forming  a 
notable  exception  to  this.  The  outline  of  the  hinder  end  is  often  made 
use  of  in  distinguishing  the 
different  kinds  of  wireworms. 
Their  food  habits  have  a  wide 
range :  some  feed  on  decaying 
wood  under  bark  or  elsewhere; 
others  on  fungi ;  several  groups 
are  carnivorous,  and  still 
others  feed  on  roots  or  seeds 
in  the  ground. 


FIG.  97.  FIG.  98. 

FIG.  97. — Wheat  Wireworm  (Agriotes  mancus  Say)':  a,  adult,  enlarged  about  five 
times;  b,  full-grown  larva  (Wireworm),  enlarged  about  three  times;  c,  side  view  of  last 
segment  of  larva.  (From  U.  8.  D,  A.  Bull.  156.) 

FIG.  98.— Corn  and  Cotton  Wireworm  (Horistonotus  uhleri  Horn) :  a,  adult,  enlarged 
about  ten  times;  b,  full-grown  larva  (Wireworm),  enlarged  over  four  times.  (From  U.  S. 
D.  A.  Bull.  156.) 

One  of  the  largest  insects  of  this  family  found  in  the  United  States 
is  the  Eyed  Elater  (Alaus  oculatus  L.),  which  is  about  an  inch  and  a  half 
long;  the  elytra  black,  finely  marked  with  white  dots;  and  with  a  pair  of 
large,  oval,  velvety-black  spots  rimmed  with  white  on  the  pronotum 
(Fig.  99).  The  larvae  of  this  insect  feed  on  insects  in  decaying  wood, 
often  that  of  the  apple,  but  are  of  little  economic  importance, 


THE  COLEOPTERA 


109 


In  the  South  and  also  in  the  West  Indies  and  Mexico  are  species 
of  Elaterids  (Pyrophorus  spp.)  which  have  an  oval,  yellowish  spot  near 
each  hinder  corner  of  the  pronotum  (Fig.  100),  and  also  an  area  on  the 
underside  of  the  abdomen  close  to,  and  partially  concealed  by  the  meta- 
thorax,  which  are  luminous,  producing  an  intermittent,  greenish-yellow, 
quite  brilliant  light,  making  the  insects  very  noticeable  at  night.  They 
are  beneficial,  the  larvae  feeding  on  white  grubs. 

The  injurious  members  of  this  family  are  those  wire  worms  which  feed 
on  seeds  and  the  roots  of  plants,  and  there  are  many  kinds  which  have 

this  habit.  Some  attack  wheat;  others 
corn,  and  still  others  feed  on  cotton, 
grass,  potatoes,  sugar-beets  and  other 
crops,  doing  much  damage.  Some  are 
most  abundant  in  heavy  soils  containing 


FIG.  99.  FIG.  100. 

FIG.  99. — Adult  Eyed  Elater  (Alaus  oculatus  L.),  about  natural  size.  (From  Linville 
and  Kelly,  General  Zoology,  Ginn  and  Company,  Publishers.) 

FIG.  100. — A  Luminous  Elaterid  (Pyrophorus  sp.)  showing  luminous  spots  on  sides 
of  pronotum.  Natural  size.  (Original.) 

much  vegetable  matter,  while  others  prefer  high,  sandy  land.  So  many 
species  of  wire-worms  are  injurious  and  so  unlike  are  their  habits  in 
different  parts  of  the  country  that  each  kind  seems  to  require  treatment 
especially  adapted  to  it. 

Control. — Some  general  factors  in  control  may,  however,  be  suggested. 
When  wireworms  are  abundant  in  low,  poorly  drained  land,  drainage 
will  be  of  much  assistance.  When  they  attack  grass  roots  in  great 
numbers,  it  is  desirable  in  cultivating  such  places  to  substitute  field  peas, 
buckwheat,  or  some  crop  not  closely  related  to  grass,  for  the  first  crop,  if 
possible,  even  though  this  does  violence  to  the  general  ideas  of  crop 
rotation.  When  sod  land  is  to  be  planted,  plowing  it  in  July  and  cultivat- 
ing often  and  deeply  the  rest  of  the  summer  will  destroy  many  of  the 
insects.  In  the  South  and  in  arid  regions,  however,  the  insects  go  deeply 


110  APPLIED  ENTOMOLOGY 

into  the  ground  during  hot  or  dry  weather,  beyond  reach  by  cultivation. 
In  such  cases  planting  early  in  the  season  and  forcing  the  plants  ahead  by 
fertilizers  and  frequent  cultivation  are  helpful.  As  the  underground 
feeding  period  of  these  insects  is  from  3  to  6  years,  proper  treatment 
for  a  single  season  will  at  best  give  only  partial  relief,  and  to  obtain  the 
most  successful  control  the  special  habits  of  the  particular  species 
concerned  should  be  ascertained,  and  control  measures  to  correspond 
be  adopted.  Various  methods  for  the  protection  of  planted  seed  have 
been  tried  but  the  results  have  not  agreed  in  all  cases  and  further 
studies  along  this  line  are  needed. 

The  Elateridse  is  one  of  the  most  important  groups  of  beetles  from  an 

economic  standpoint,  and  injurious  species  occur  practically  everywhere 

in  the  United  States.     Several  hundred  kinds  are  known  in  this  country. 

Family   Scarabseidae    (Lamellicorn    beetles). — This   is   a   very  large 

and  important  family  of  beetles,  containing  many  pests.     The  antennae 

in  this  group  have  several  of  the  terminal  segments 
large,  flattened,  and  broader  on  one  side,  movable 
but  generally  carried  close  together.  The  insects 
are  stout  and  rather  short  in  most  cases,  and 
the  elytra  usually  do  not  cover  the  entire 
abdomen. 

Based  on  their  habits,  two  sections  of  the 
family  can  be  distinguished:  the  scavengers 
which  both  as  larvae  and  adults  feed  on  decaying 
matter;  and  the  leaf  chafers  which  as  adults 
generally  consume  leaves  or  flowers,  and  whose 


FIG.  101.  —  Egyptian    larvae  occur  in  the  ground  feeding  on  roots,  or 

carving  of  a  Secarabaeus.  •,  i 

(Original.)  m  decaying  wood. 

The  Scavengers,  though  they  may  be  con- 
sidered as  beneficial,  are  not  of  great  importance,  but  some  species 
because  of  their  peculiar  habits  have '  attracted  attention  for  centuries. 
The  habit  referred  to  is  that  shown  by  some  of  the  so-called  "  Tumble- 
bugs"  in  connection  with  egg  laying.  A  pair  of  these  beetles  will  to- 
gether form  a  little  dung  into  a  ball  which  they  then  begin  to  roll  over 
the  ground,  often  for  a  long  distance.  Finally  they  bury  it  in  the 
ground  after  an  egg  has  been  laid  upon  it,  thus  providing  partially 
decomposed  food  for  the  larva.  The  Sacred  beetle  or  Scarabseus  of 
the  Egyptians  was  one  of  the  insects  of  this  group  (Fig.  101)  and  has 
been  preserved  in  their  drawings  and  carvings  as  a  symbolic  record 
of  their  beliefs.  The  leaf  chafers  form  the  larger  part  of  the  family. 
Among  them  are  a  number  of  serious  pests. 

The  June  Bugs  or  May  Beetles  (Phyllophaga  and  other  genera). — 
This  is  a  group  of  beetles  quite  similar  both  in  appearance  and  habits. 
The  adults  are  generally  dark  brown  and  rather  glossy  above,  from  half 


THE  COLEOPTERA 


111 


an  inch  to  an  inch  long,  and  very  stout  (Fig.  102).  They  appear 
during  the  spring  months,  earlier  in  the  South  than  in  the  North, 
flying  at  night  and  are  attracted  by  lights,  to  which  they  fly  in  a  clumsy, 
erratic  way.  They  feed  at  night  on  the  leaves  of  various  trees,  often 
entirely  stripping  them.  Different  kinds  of  June  bugs  appear  to  prefer 
different  kinds  of  trees  for  their  food.  Some  species  seem  to  select  the 
oak,  others  the  ash,  still  others  the  pine.  Small  birches  have  been 
completely  stripped  of  their  foliage  in  a  single  night.  In  the  South  two 
species  appear  to  prefer  the  longleaf  pine  and  whatever  the  species, 
large  areas  of  timber  may  be  defoliated  when  the  beetles  are  abundant, 
(hough  this  seldom  appears  to  be  the  case  in  New  England.  On  the 
Pacific  Coast  too,  though  June  bugs  occur,  they  do  not  seem  to  be  as 
important  as  in  the  interior  of  the  country,  particularly  in  the  Mississippi 
Valley  and  as  far  north  as  the  Great  Lakes. 


FIG.  102. 


FIG.  103. 

FIG.  102. — Adult  "June  Bugs,"  female  and  male,  natural  size.  (From  U.  S,  D.  A. 
Farm.  Bull.  940.) 

FIG.   103. — Full-grown  larva  (white  grub)  of    "June  Bug,"  natural  size.      (Original.) 

The  eggs  of  the  June  bugs  are  laid  in  the  ground  and  hatch  in  a  few 
weeks  into  tiny  " white  grubs"  with  brown  heads  and  legs,  and  soft, 
white  bodies  which  increase  in  size  toward  the  hinder  end.  The  grub 
(Fig.  103)  as  usually  found  when  dug  up  is  curled  through  the  greater  part 
of  a  circle  and  this  is  very  characteristic,  only  a  few  other  beetle  larvae 
(and  those  belong  in  the  same  family)  greatly  resembling  it.  The  grubs 
feed  during  the  summer  on  decaying  vegetation  and  living  plants  close  to 
the  surface  of  the  ground  but  on  the  approach  of  cold  weather  go  deeper 
into  the  ground  to  pass  the  winter.  The  following  spring  they  come  up 
near  the  surface  again  and  now  feed  on  the  plant  roots,  causing  in  this, 
their  second  season,  the  largest  injury.  In  the  fall  of  the  second  season 
they  again  go  deep  into  the  ground  to  pass  the  winter,  coming  up  the 
third  spring  to  feed  on  plant  roots  until  June  or  July,  when  they  go  down 
a  little,  though  not  usually  much  if  any  below  where  they  may  be  reached 
by  deep  plowing.  Here  they  transform  to  pupae  which  become  adult 


112  APPLIED  ENTOMOLOGY 

after  a  month  or  two,  but  the  beetles  remain  in  these  underground  pupal 
cells  until  the  next  (fourth)  spring,  when  they  emerge.  The  length  of  a 
generation  as  thus  outlined  therefore  is  3  years,  but  the  progeny  of  any 
given  beetle  appearing  one  spring  will  appear  the  spring  of  the  fourth  year 
following,  i.e.,  a  generation  requires  3  years  but  is  present  in  parts  of  4 
calendar  years. 

This  life  history  holds  for  most  of  the  injurious  species  of  June  bugs 
in  the  Central  States,  through  the  country  east  of  the  Rocky  Mountains. 
In  the  North,  however,  the  life  history  in  some  cases  at  least,  requires  4 
years,  while  in  the  Southern  States  2  years  appears  to  be  the  normal  period. 
Some  appear  every  year  though,  indicating  the  existence  of  three  broods 
in  those  regions  where  the  3-year  life-history  exists,  but  the  size  of  these 
broods  is  markedly  different.  Though  undoubtedly  subject  to  factors 
which  may  increase  or  decrease  the  size  of  these  broods  as  years  pass,  the 
most  abundant  and  destructive  one  at  present  is  that  in  which  the  beetles 
appeared  in  1917  and  1920,  and  which  will  reappear  at  3-year  intervals 
hereafter,  the  greatest  destruction  being  caused  by  the  grubs  the  following 
year.  The  second  brood,  the  beetles  of  which  appeared  in  1918,  was  not 
of  sufficient  size  to  attract  much  attention  by  their  injuries  in  1919  and 
probably  will  not  be  important  in  1922,  while  the  third  brood  with  the 
beetles  in  1919  and  their  injuries  in  1920  was  of  importance  in  only  a  few 
areas.  How  soon  favoring  conditions  may  lead  to  one  of  these  last-named 
broods  becoming  large  enough  to  be  important,  or  unfavorable  factors 
reduce  the  importance  of  the  first-mentioned  one,  cannot  be  predicted. 

Though  white  grubs  have  many  natural  enemies,  including  numerous 
mammals,  birds  and  insects,  and  also  several  diseases,  both  bacterial  and 
fungous,  they  are  not  sufficient  checks  to  prevent  considerable  injury. 

Control. — Pasturing  hogs  in  fields  considerably  infested  by  white 
grubs  is  a  good  practice,  the  hogs  feeding  on  other  insects  they  find  in  the 
ground,  as  well.  Poultry  can  be  made  use  of  in  the  same  way,  but  this  is 
most  effective  when  the  ground  is  being  cultivated.  Rotation  of  crops 
is  also  of  value  if  used  intelligently.  Corn  and  clover  are  crops  in  which 
the  beetles  will  not  lay  eggs  freely.  Grain  fields  have  many  eggs  laid  in 
them,  but  if  followed  by  clover  the  grubs  will  do  little  damage.  Fall 
plowing  before  the  grubs  go  down  to  pass  the  winter  will^destroy  many  of 
them.  This  should  be  done  as  late  before  the  grubs  start  down  as  possible. 
The  spring  after  beetles  were  abundant  the  year  before,  many  small  grubs 
should  be  found  in  cultivating.  In  this  case  seed  with  small  grain  or 
clover.  If  large  grubs  are  abundant  either  in  the  fall  or  the  following 
spring,  plant  late  if  possible,  as  the  grubs  finish  feeding  before  July  in 
most  cases;  or  plow  as  soon  after  July  15  as  possible,  to  break  up  and 
destroy  the  pupae.  Where  beetles  are  stripping  foliage,  spraying  with  a 
stomach  poison,  standard,  or  a  little  above  standard  strength,  is  a  good 
treatment  where  conditions  are  such  as  to  make  it  practicable. 


THE  COLEOPTERA 


113 


In  general  the  treatment  can  be  based  on  the  year  the  beetles  are 
abundant.  Sod  land  broken  up  that  year  should  be  plowed  before  Octo- 
ber and  should  not  be  in  corn  or  potatoes,  but  in  clover,  small  grain  or 
buckwheat  the  next  year,  if  the  farm  practice  of  that  region  will  permit. 
The  following  year  delay  planting  till  as  late  as  possible.  Pasture  every 
season  with  hogs  in  the  fall  as  soon  as  the  crop  is  out. 

The  Rose  Chafer  (Macrodactylus  subspinosus  Fab.). — This  insect  occurs  all 
over  the  Eastern  United  States  as  far  south  as  Virginia  and  Tennessee  and  west  to 
Colorado,  being  particularly  abundant  and  destructive  in  sandy  localities.  The 
adult  beetle  is  about  a  third  of  an  inch  long,  rather  stout,  though  less  so  in  pro- 


FIG.  104. — Rose  Chafer  (Macrodactylus  subspinosus  Fab.):  «,  adult  beetle;  b,  larva 
(grub) ;  e,  pupa;  /,  injury  to  leaves  and  blossoms  of  grape  with  beetles  at  work.  Fine  lines 
beside  a,  b,  and  e,  show  the  true  length:  /,  somewhat  reduced.  (From  U.  S.  D.  A.  Farm. 
Bull.  721.) 

portion  to  its  length  than  are  the  June  bugs,  dull  yellow,  with  pale,  red  legs  which 
are  long  and  slender.  It  appears  about  the  time  roses  begin  to  bloom,  i.e.,  in 
May  in  the  South,  and  in  June  in  the  more  northern  part  of  its  range,  and  attacks 
a  large  number  of  plants.  It  seems  originally  to  have  been  a  rose  feeder:  later 
it  became  a  serious  pest  of  the  grape  and  is  now  destructive  to  many  fruit  and 
shade  trees  and  shrubs,  and  even  to  garden  fruits  and  vegetables  when  abundant, 
eating  blossoms,  leaves  and  any  fruit  which  may  be  available  during  its  adult 
condition  (Fig.  104). 

The  eggs,  about  thirty  in  number,  are  laid  a  little  below  the  surface  of  the 
ground,  sandy  land  being  apparently  somewhat  preferred,  and  these  hatch  in 
2  to  3  weeks  into  tiny  white  grubs  somewhat  resembling  those  of  the  June  bugs. 

8 


114  APPLIED  ENTOMOLOGY 

These  grubs  feed  on  plant  roots,  particularly  those  of  grass,  until  quite  late  in  the 
fall,  then  work  down  in  the  ground  to  below  the  frost  line,  where  each  forms  a 
small  earthen  cell  in  which  to  winter.  In  the  spring  pupation  takes  place  and 
from  2  to  4  weeks  later  the  adult  beetle  is  produced  and  digs  its  way  to  the  surface. 
An  adult  individual  lives  about  3  weeks. 

Control. — Stomach  poisons  will  kill  the  adults  in  time  but  they  work  too 
slowly  to  save  the  plants,  which  are  seriously  injured  before  the  beetles  die. 
In  any  case,  these  could  hardly  be  used  on  flowers  as  they  would  at  least  mar  their 
appearance.  On  grapes  and  other  fruits,  arsenate  of  lead,  using  5  Ib.  of  the  paste 
in  50  gal.  of  water  or  Bordeaux  mixture  (better),  applied  very  thoroughly  as  soon 
as  the  beetles  appear,  or  just  before  the  blossoms  open  in  the  case  of  the  grape, 
has  given  fair  results,  though  a  second  treatment  just  after  the  blossoms  fall  is 
sometimes  needed.  With  stone-fruit  trees  the  self-boiled  lime-sulfur  wash  should 
be  used  instead  of  the  Bordeaux. 

Hand  picking,  though  tedious,  is  effective  with  plants  growing  low  enough  to 
make  this  method  of  control  practicable,  but  must  be  repeated  every  day  to  get 
those  which  fly  to  the  plants  from  elsewhere,  or  emerge  from  the  ground  later. 
Bagging  the  clusters  of  grapes  is  often  practiced  where  this  plan  seems  worth 
while.  Harrowing  the  breeding  grounds  of  the  insect  to  a  depth  of  three  or  four 
inches,  during  the  time  they  are  pupae,  i.e.,  the  latter  part  of  May  for  the  central 
part  of  their  range,  destroys  many  of  the  pupa3  which  appear  to  be  very  easily 
killed  by  any  disturbance  while  in  this  stage.  The  difficulty  with  this  is  to  locate 
the  areas  where  they  are  breeding  most  abundantly.  Light,  sandy  ground  will 
generally  prove  to  be  the  place  for  such  treatment. 

This  insect  seems  to  have  a  poisonous  effect  when  eaten  by  small  chickens, 
many  dying  within  a  day  or  two  after  feeding  on  Rose  Chafers. 

On  the  Pacific  Coast  several  species  of  Hoplia  seem  to  play  much  the  same 
role  as  the  Rose  Chafer  does  in  the  East.  Their  life  history  does  not  appear  to 
have  been  worked  out  but  probably  does  not  differ  greatly  from  that  of  the  Rose 
Chafer,  and  the  treatments  are  practically  the  same.  The  beetles  of  all  the 
species  range  from  about  one-quarter  to  one-half  an  inch  in  length  and  are  light 
brown,  grayish,  mottled,  or  black  with  brown,  orange-yellow  or  olive,  either  in 
spots  or  entirely  concealing  the  black.  Grape,  rose,  greasewood,  blackberry,  etc., 
are  the  chief  food  plants. 

The  Green  Japanese  Beetle  (Popillia  japonica  Newst.)  has  recently  been 
discovered  in  New  Jersey.  The  beetles  attack  the  foliage  of  many  kinds  of 
plants  including  fruit  trees,  small  fruits,  garden  crops  and  ornamental  trees  and 
shrubs:  the  larvae  feed  on  the  roots  of  plants  and  on  decaying  vegetable  matter. 
The  beetle  is  about  half  an  inch  long  and  somewhat  resembles  several  of  our  native 
forms.  If,  in  spite  of  vigorous  measures  now  being  taken  to  eradicate  it,  this 
insect  should  become  widely  distributed,  it  will  undoubtedly  become  a  serious 
pest  as  it  already  is  in  Japan. 

Many  other  Scarabseids  are  occasionally  injuriously  abundant  in 
different  parts  of  the  country  but  can  hardly  be  considered  as  of  nation- 
wide importance.  The  largest  beetles  found  in  the  United  States  also 
belong  here  and  are  called  rhinoceros  beetles.  One  species,  Dynastes 


THE  COLEOPTERA 


115 


lityrus  L.  (Fig.  105),  about  two  and  one-half  inches  long,  is  greenish-gray 
with  black  spots  on  the  elytra.  The  male  has  a  long  horn  on  the  head, 
projecting  forward  and  upward,  and  another  projecting  forward  from  the 
pronotum.  The  female  has  only  a  small  tubercle  on  the  head.  It  occurs 
in  the  Southern  States.  In  another  species  found  in  the  West  the  pro- 
thoracic  horn  is  much  longer. 


FIG.  105. — Rhinoceros    Beetle    (Dynastes    tityrus    L.),    about    natural    size.     (Original.) 

Family  Chrysomelidse  (Leaf  beetles). — This  is  the  largest  family  of 
beetles  but  its  members  are  small,  not  often  being  over  half  an  inch  long. 
Most  of  them  are  leaf  feeders,  though  the  larvae  of  a  few  are  worm-like 
and  attack  underground  stems  or  roots.  Many  are  serious  pests,  and 
though  almost  none  are  found  throughout  the  entire  country,  allied  species 
working  in  similar  ways,  occur. 

In  the  group  as  a  whole,  yellowish  elytra  with  black  lines  or  spots 
seems  to  be  the  prevailing  color  pattern,  though  of  course,  with  many 
exceptions.  Together  with  the  next  two  families,  from  which  other 
characters  separate  this  one,  the  third  segment  of  the  tarsus  is  generally 
broad,  being  drawn  out  into  a  lobe  on  each  side,  and  is  covered  beneath 
with  minute,  closely  set  hairs  (pubescent).  The  antennae  are  at  most, 
of  only  average  length. 

The  Colorado  Potato  Beetle  (Leptinotarsa  decimlineata  Say).— 
This  well-known  insect  was  discovered  about  1823  by  Long's  exploring 
expedition  to  the  Rocky  Mountains,  in  the  region  of  the  upper  Missouri 
River.  Its  food  there  was  the  Buffalo-bur  (Solanum  rostratum  Dunal) 
and  the  insect  was  apparently  not  remarkably  abundant,  and  certainly 
of  no  economic  importance,  nor  did  it  become  so  until  civilization,  and 
with  this  the  potato,  reached  that  territory.  Then  a  new  and  satis- 
factory food  plant,  abundant  enough  to  provide  all  the  insects  with  food 
became  available  and  the  potato  beetle  increased  in  numbers  and  began 
to  spread  to  the  East.  At  first  its  rate  of  spread  was  only  about  50 
miles  a  year  but  after  crossing  the  Mississippi  River  this  became  more 
rapid  and  it  reached  the  Atlantic  Coast  about  1874.  Since  then  it  has 
spread  both  northward  and  southward  until  it  is  now  found  practically 


116  APPLIED  ENTOMOLOGY 

everywhere  east  of  the  Rocky  Mountains  where  the  potato  is  grown  and 
it  has  also  reached  the  Pacific  Coast.  It  does  not  apparently  thrive 
in  the  hot  climate  of  the  more  southerly  States. 

The  adult  beetle  (Fig.  1066)  is  somewhat  less  than  half  an  inch  long 
and  about  two-thirds  this  width,  its  back  rather  high  and  rounded.  It 
is  clay-yellow  and  has  10  longitudinal  black  lines  on  its  elytra.  The  head 
has  a  black  spot  above,  and  the  pronotum  has  a  number  of  irregular  spots. 
Winter  is  spent  as  the  adult  in  the  ground  but  the  insects  come  out  quite 
early  in  the  spring.  As  soon  as  the  potatoes  are  up,  they  begin  to  feed 
and  soon  lay  their  eggs,  placing  these  on  the  under  surface  of  the  leaves 

t . in  small  clusters,  an  individual,  lay  ing  500 

or  more  in  all.  They  are  small,  yellow 
e&gs  wnicn  hatch  in  from  4  days  to  a  week 
or  more,  according  to  the  temperature. 
^e  Srubs  or  "slugs"  as  they  are  often 
called  (Fig.  106a)  are  dull  brick-red,  soft 
and  with  fat  bodies.  They  feed  for  from 


a  b  2  to  3  weeks,   then    go    into    the    ground 

FIG   106.  — Colorado   Potato     wnere  they  pupate  for  a  week  or  two,  after 

Beetle    (Leptmotarsa  decimhneata 

Say),   slightly  enlarged:  a,  full-     which  the  adults  emerge  and  lay  eggs  for  a 
grown  larva  (Grub);  adult  Beetle.     second  generation,  the  adults  of  which  ap- 

(From  Berlese,   After   U.    S.    BUT.  &         .  ' 

Eut.  Cire.  87.)  pear  early  in  the  fall.  This  second  gen- 

eration of  beetles  feeds  for  a  time,  then  in 
September  or  October  enters  the  ground  to  pass  the  winter. 

As  the  eggs  of  this  insect  are  not  all  laid  at  one  time,  different  ages 
and  different  stages  even,  may  be  found  together  in  the  same  field.  And 
as  the  adults  feed  in  the  spring  during  their  egg-laying  period,  as  do  the 
two  generations  of  adults  produced  during  the  season,  in  addition  to  the 
two  generations  of  grubs  which  also  consume  the  leaves,  the  plants  are 
being  attacked  much  of  the  time. 

While  the  potato  appears  to  be  the  preferred  food  of  this  insect,  other 
members  of  the  nightshade  family  are  sometimes  attacked,  particularly 
the  tomato  and  eggplant. 

Control. — This  pest  is  easily  controlled  by  spraying  with  either 
of  the  stomach  poisons  and  as  the  potato  is  quite  resistant  to  poisons,  the 
strength  of  the  mixture  can  with  safety  be  somewhat  increased  above 
that  of  the  standard  formula.  The  chief  difficulty  in  control  is  that  as 
the  beetles  attack  the  rapidly-growing  plant  as  soon  as  it  appears  above 
ground,  the  spray  should  be  applied  then,  while  a  week  later  a  large 
amount  of  new  growth  which  has  no  poison  on  it  will  have  developed, 
upon  which  the  insects  can  feed.  To  avoid  this,  spraying  during  the 
period  of  rapid  growth  needs  to  be  done  more  frequently  than  is  the  case 
with  most  plants.  Two  or  three  treatments,  however,  will  generally  be 
sufficient,  and  a  combination  with  Bordeaux  mixture  is  advantageous 
where  arsenate  of  lead  is  the  stomach  poison  used. 


THE  COLEOPTERA  117 

On  small  areas,  Paris  green  dry,  mixed  with  10  to  20  parts  of  some 
inert  material,  dusted  over  the  plants,  preferably  while  the  dew  is  on 
them,  is  a  fair  treatment,  and  this  poison  as  a  spray  can  also  be  used. 
Arsenate  of  lead  is  at  present  the  preferred  poison  for  this  pest,  however. 

Various  birds,  skunks,  snakes  and  toads  feed  on  the  Colorado  Potato 
Beetle  to  some  extent,  and  it  also  has  numerous  insect  enemies. 


The  history  of  the  development  of  the  Colorado  Potato  Beetle,  from 
an  unimportant,  even  probably  a  rather  uncommon  insect,  feeding  upon 
a  plant  of  no  value  to  man,  into  one  of  the  most  abundant  and  widely 
distributed  of  our  pests,  attacking  and  seriously  injuring  an  important 
crop,  is  a  suggestive  one.  In  a  division  of  the  insects  of  the  United 
States  into  those  which  are  injurious  as  regards  man  and  his  various 
interests;  those  which  are  beneficial,  and  those  which  are  of  little  or  no 
economic  importance  either  way,  we  shall  find  that  the  last  group  is  by 
no  means  a  small  one.  How  many  species  in  this  group  are  there  which 
are  potential  pests?  It  is  true  that  the  making  available  of  a  new  food 
plant  to  which  the  Colorado  Potato  Beetle  could  turn,  was  probably  the 
chief  factor  in  this  particular  case,  but  any  insect  which  for  some  reason 
changes  from  an  unimportant  food  plant  to  a  crop  plant  may  at  once 
become  a  pest.  Thus  another  Chrysomelid  only  a  little  smaller  than  the 
Colorado  Potato  Beetle  and  closely  related  to  it,  the  Three-spotted  Do- 
ryphora  (Doryphora  divicollis  Kirby) ,  which  feeds  on  milkweed)  is  now  of 
practically  no  importance.  But  if  it  should  change  its  food  to  some 
valuable  crop  plant  it  would  at  once  become  an  important  addition  to 
the  list  of  insect  foes  man  has  to  combat.  Several  such  cases  are  al- 
ready known.  How  many  others  may  appear  as  the  changing  conditions 
which  always  accompany  an  increasing  population  and  the  consequent 
changes  in  plant  population  take  place,  no  one  can  predict.  Some  species 
of  plants  once  common  are  rapidly  disappearing.  As  they  go,  will  the 
insects  feeding  on  them  go  too,  or  will  they  be  able  to  find  another  food 
plant,  and  will  this  one  be  of  value  to  man?  The  appearance  of  new 
pests  in  such  ways  may  come  at  any  time,  and  the  fact  that  an  insect  is 
not  now  a  pest  should  not  lead  to  its  being  ignored,  for  it  may  have  great 
potential  importance.  The  Murky  Ground  Beetle  (Harpalus  caliginosus 
Fab.)  is  now  mainly  a  carnivorous  beetle,  but  sometimes,  though  rarely, 
attacks  the  strawberry.  If  it  should  turn  to  this  latter  plant  entirely 
for  its  food,  another  important  pest  would  be  added  to  our  list  and  lost 
from  among  our  friends. 

Such  facts  call  for  as  complete  a  knowledge  as  possible  of  the  life 
and  habits  of  all  insects  whether  now  beneficial  or  only  of  no  economic 
importance,  in  order  that  we  may  have  the  knowledge  of  them  and 
their  ways  which  is  necessary  in  case  they  should  become  injurious. 


118 


APPLIED  ENTOMOLOGY 


The  Striped  Cucumber  Beetle  (Diabrotica  vittata  Fab.). — The  com- 
mon Cucumber  beetle  is  found  everywhere  in  this  country  (of  which  it  is  a 
native)  east  of  the  Rocky  Mountains.  It  is  a  small  beetle  about  a  fifth  of 
an  inch  long,  with  a  black  head,  yellow  pronotum  and  three  black  stripes 
along  its  yellow  elytra  (Fig.  107).  The  insect  passes  the  winter  as  the 
adult  beetle  in  protected  places,  probably  among  dense  weed  growth. 
It  leaves  its  winter  quarters  early  in  the  spring,  before  any  of  its  culti- 
vated food  plants  are  available,  and  feeds  on  blossoms  of  various  kinds 
until  cucumbers,  squashes  and  the  other  cucurbits  which  are  its  favorite 
food  plants  are  available.  It  then  attacks  these  and  may  also  seriously 
injure  peas,  beans,  apples,  and  later  in  the  season,  corn.  It  lays  its 
eggs  either  singly  or  in  clusters,  in  the  ground 
near  the  stems  and  roots  of  the  cucurbits,  often 
in  crevices  of  the  soil,  the  total  number  of  eggs 
per  beetle  varying  from  a  few  hundred  to  over  a 
thousand.  The  eggs  hatch  in  a  week  or  two,  ac- 
cording to  the  temperature  at  that  time,  and  the 
grubs  feed  on  the  stems  and  roots.  They  are  tiny, 
white,  slender,  and  resemble  maggots  more  than 
the  usual  forms  of  beetle  larvae,  and  when  full 
grown,  after  2  to  5  or  more  weeks,  according  to  the 
temperature,  are  only  about  three-tenths  of  an 
They  then  soon  change  to  pupae,  still 


FIG.    107.  — Adult 
Striped  Cucumber  Beetle     inch  long. 

(Diabrotica  mttata  Fab.)    in  the   grounci7   jn   which   stage   they  remain  for 


enlarged  about  six  times 

(see  hair  line   for  true    about  a  week  before  the  beetles  emerge. 

length).       (From    U.    S. 
D.  A.  Farm.  Bull.  1038.) 


The  life 


cycle  therefore  varies  in  length  according  to  the 
temperature,  it  being  perhaps  not  over  4  weeks  in 
the  South  and  8  in  the  more  northern  States.  This  gives  time  for 
several  generations  each  season,  and  though  in  the  North  there  is 
apparently  but  one,  this  number  increases  farther  south  until  in  Texas 
there  may  be  four. 

The  destruction  caused  by  these  insects  when  they  are  abundant  is 
often  very  great.  Their  first  attacks  come  just  when  the  young  plants 
are  struggling  to  establish  themselves  and  the  feeding  of  the  adult 
beetles  is  often  sufficient  to  kill  them.  Later  in  the  season  the  beetles 
continue  feeding  on  the  leaves  and  stems,  reducing  the  vigor  of  the  plant 
and  its  productiveness,  and  they  may  also  feed  on  the  outer  surface  of 
the  fruit,  making  it  more  or  less  unsalable.  They  also  frequently  enter 
greenhouses  and  attack  cucurbits  there.  The  larvae  affect  the  vitality 
of  the  plant  by  attacking  the  underground  stems  and  roots  but  are  less 
injurious  than  the  adults. 

The  beetles  are  also  injurious  by  carrying  the  "bacterial  wilt" 
disease  and  " cucurbit  mosaic"  disease,  not  only  from  plant  to  plant, 
but  also  from  one  season  to  the  next.  As  these  diseases  are  serious  ones, 


THE  COLEOPTERA  119 

often  destroying  plants,  this  adds  to  the  importance  of  the  insect  as  a 
pest. 

On  the  Pacific  Coast  is  a  slightly  larger  species  known  as  the  Western 
Striped  Cucumber  beetle  (Diabrotica  trivittata  Mannerh.)  which  has  much 
the  same  habits  as  the  eastern  form.  In  the  more  southerly  portion  of 
this  region  the  adults  are  more  or  less  active  during  the  cold  months. 
There  appear  to  be  at  least  two  generations  a  year,  and  the  methods  given 
below  for  the  control  of  the  eastern  species  also  apply  for  this  one. 

Control. — This  is  a  difficult  insect  to  control,  particularly  where  large 
areas  are  planted  to  any  of  the  cucurbits  and  small  garden  methods  will 
not  pay.  Protective  methods,  practicable  in  gardens,  enable  the  plants 
to  get  well  started,  after  which  they  are  able  to  grow  and  produce  the  crop 
to  quite  an  extent,  despite  the  insect.  Screening  the  plants  before  they 
come  up,  using  fine-mesh  wire  or  thin  cheese-cloth  stretched  over  a 
frame,  works  well  for  this  purpose,  provided  the  edge  of  the  frame  fits 
tightly  into  the  earth  everywhere,  so  that  the  beetles  cannot  burrow  un- 
der it.  Sometimes  an  excess  of  seed  is  planted  with  the  idea  of  giving 
the  insects  enough  food  so  that  few  or  none  of  the  plants  will  be  too  thickly 
infested  to  be  able  to  live,  and  the  poorest  ones  can  be  thinned  out  later. 
Gathering  all  but  a  few  of  the  plants  as  soon  as  the  crop  has  been  har- 
vested, and  burning  them  will  leave  the  others  for  the  beetles  to  gather 
on.  These  can  then  be  sprayed  with  a  strong  stomach  poison  or  a  strong 
contact  insecticide.  Early  cucurbits  such  as  gourds,  can  be  planted  near 
later  cucumbers  and  will  act  as  trap  plants,  attracting  the  beetles. 

Spraying  with  a  stomach  poison,  either  alone  or  with  Bordeaux 
mixture,  is  a  good  treatment  if  both  sides  of  the  leaves  and  the  stems  are 
well  covered.  Arsenate  of  lead  6  Ib.  of  paste  in  50  gal.  of  water  seems 
generally  to  give  the  best  results.  The  addition  of  3  Ib.  of  soap  to  each  50 
gal.  of  spray  makes  the  latter  adhere  better  to  the  plant.  Arsenate  of 
lime  gives  fair  results.  Dusting  the  plants  with  the  dry  poison  mixed 
with  air-slaked  lime  or  plaster,  at  the  rate  of  1  Ib.  of  the  poison  to  any- 
where from  25  to  50  Ib.  of  the  inert  material,  sometimes  works  well. 
Its  weakness  as  a  treatment  is  mainly  that  it  is  difficult  to  get  it  onto  the 
under  side  of  the  leaves  and  have  it  stay  there. 

Whatever  spray  material  is  used,  give  the  first  treatment  as  soon  as 
the  plants  show  above  ground  and  repeat  two  or  three  times  at  about 
weekly  intervals,  or  oftener  if  rain  makes  it  necessary. 

Several  other  minor  remedies  such  as  dusting  the  plants  while  the 
ground  is  moist,  with  tobacco  dust,  lime,  or  a  mixture  of  the  two;  and 
hastening  the  growth  and  increasing  the  vigor  of  the  plants  by  fertilizers 
and  frequent  cultivation,  have  some  merit.  If  any  or  all  the  above-sug- 
gested treatments  have  been  used,  however,  some  of  the  insects  will 
generally  be  present,  none  of  these  methods  giving  absolute  freedom  from 
the  pest. 


120 


APPLIED  ENTOMOLOGY 


The  Corn-root  Worms. — There  are  several  species  of  the  genus  Diabrotica 
which  as  larva?  appear  to  make  a  specialty  of  feeding  either  upon  the  base  of  the 
stem  or  the  roots  of  corn. 

The  Southern  Corn-root  worm  or  Twelve-spotted  Cucumber  beetle  (Diabrot- 
ica duodecimpunctata  Oliv.)  is  found  practically  everywhere  in  the  United  States 
east  of  the  Rocky  Mountains,  but  is  usually  a  serious  pest  only  from  Maryland 
to  Florida  and  as  far  west  as  southern  Ohio,  Indiana  and  Illinois,  Alabama, 
Louisiana  and  Texas.  The  insect  generally  winters  as  the  adult  beetle  (Fig.  108) 
under  rubbish  or  in  other  protected  places,  except  in  the  far  South  where  it  is 


FIG.  108.  FIG.  109. 

FIG.  108. — Adult  Southern  Corn-root  Worm  (Diabrotica  duodecimpunctata  Oliv.), 
enlarged  about  eight  times.  (From  U.  S.  D.  A.  Farm.  Bull.  950.) 

FIG.  109. — Grub  of  Southern  Corn-root  Worm  and  its  burrow  in  corn.  Much  en- 
larged. (From  U.  S.  D.  A.  Farm.  Bull.  950.) 

more  or  less  active  during  this  period.  In  spring  it  lays  its  eggs  just  below  ground, 
on  or  near  the  young  corn  plants,  and  the  tiny  grubs  which  hatch,  attack  the  corn, 
feeding  on  the  roots  and  drilling  into  the  stem  just  above  them,  boring  out  the 
crown  and  killing  the  bud  (Fig.  109).  From  this  habit  the  insect  is  often  called 
the  "  bud  worm"  or  "drill  worm."  Small  plants  injured  in  this  way  break  off 
at  the  crowns  when  pulled,  and  larger  ones  become  dwarfed  and  yellowish. 
Other  plants  such  as  wheat,  millet,  alfalfa,  etc.,  are  also  attacked  by  the  larvse. 
The  adult  beetle  is  about  a  quarter  of  an  inch  long,  yellowish-green  with  black 
head  and  legs  and  twelve  black  spots  on  its  back.  It  feeds  on  squashes,  cucum- 
bers and  many  other  plants.  There  appear  to  be  two  generations  each  year  in  the 
North  and  three  in  the  South,  but  most  of  the  injury  is  caused  by  the  first  genera- 
tion. Burning  over  waste  places  where  there  is  rubbish,  during  the  cold  months 
or  on  cold  days  will  destroy  many  of  the  beetles  which  are  seeking  protection 


THE  COLEOPTERA 


121 


there.  A  careful  crop  rotation,  never  planting  corn  twice  in  succession  on  the 
same  land  is  also  of  value.  Cotton,  not  being  attacked  by  this  pest  is  a  safe  crop 
to  follow  corn  and  a  legume  is  desirable  in  the  rotation.  The  insect  is  most 
serious  in  wet  seasons  and  on  low  land.  Corn  is  often  more  thickly  planted  on 
low  places  on  this  account,  to  increase  the  chance  of  getting  a  stand.  Fertiliza- 
tion and  cultivation  increase  the  vigor  and  resistance  of  the  plants  to  attack. 
In  the  far  South  corn  planted  during  April  is  more  likely  to  be  injured  than  that 
planted  before  this  time  or  after  the  tenth  of  May. 

The  Western  Corn-root  worm  (Diabrotica  longicornis  Say)  occurs  from 
Nova  Scotia  to  the  Gulf  of  Mexico  and  west  to  Minnesota,  Nebaska  and  New 
Mexico,  but  is  most  injurious  from  Ohio 
to  Tennessee  and  from  South  Dakota 
through  Nebraska,  Iowa  and  Missouri. 
The  winter  is  spent  in  the  egg  in  the 
ground  and  the  grubs  (Fig.  110)  hatch 
in  the  spring  and  attack  the  corn  roots  enlarged. 
(Fig.  Ill)  but  never  the  stem.  After 
feeding  until  full-grown  they  pupate  in  the  ground  and  the  adult  beetles 
emerge  in  July  and  August  and  lay  their  eggs.  There  is  therefore,  but 
one  generation  a  year.  The  adult  beetles  (Fig.  112)  are  about  one-fifth 
of  an  inch  long  and,  except  for  their  black  eyes,  are  entirely  greenish  or 
yellowish-green.  They  feed  on  the  pollen  and  silk  of  corn  and  on  the 


FIG.   110. — Grub  of  Western  Corn-root 
worm  (Diabrotica  longicornis  Say) ,  much 
(From  U.  S.  D.  A.  Bull.  8.) 


FIG.  111.  FIG.  112. 

FIG.  111. — Work  of  Western  Corn-root  worm  in  corn  roots.  (From  U.  S.  D.  A. 
Bull.  8.) 

FIG.  112. — Adult  Western  Corn-root  worm,  enlarged.  Hair  line  at  right  shows 
real  length.  (From  U.  S.  D.  A.  Bull.  8.) 


blossoms  and  leaves  of  other  plants,  in  August  and  September  and  if  abundant 
then  in  a  corn  field,  one  may  be  certain  that  that  field  will  be  well  stocked  with 
eggs  and  therefore  that  corn  should  not  be  planted  there  again  the  following 
spring  Corn  attacked  by  the  grubs  at  first  produces  shortened  ears  with  kernels 
lacking  at  the  tips:  later  it  fails  to  produce  the  ears,  and  dwarfing  of  the  plants 


122 


APPLIED  ENTOMOLOGY 


occurs.  Rotation  of  crops  has  proved  a  successful  control  for  this  insect  in 
practically  every  case  where  it  has  been  tried. 

Another  species  (Diabrotica  vergifera  Lee.)  having  similar  habits  and  similarly 
controlled,  is  often  destructively  abundant  in  Colorado. 

On  the  Pacific  Coast  a  different  species,  the  Western  Twelve-spotted  Cucum- 
ber Beetle  or  Flower  Beetle  (Diabrotica  soror  Lee.),  appears  to  have  the  same  gen- 
eral habits  as  its  eastern  relatives,  but  observations  thus  far  indicate  that  the 
grubs  are  injurious  mainly  to  alfalfa,  beet,  pea  and  peanut  roots,  while  the  adults 
do  much  damage  to  many  plant  leaves,  buds  and  flowers.  The  winter  appears 
to  be  spent  in  the  adult  stage  and  the  eggs  are  laid  from  March  to  May  in 
different  latitudes.  There  are  probably  two  generations  each  year.  The  adult 
is  one-fifth  to  one-fourth  of  an  inch  long.  The  head,  antennae,  legs  and  body  are 
black;  the  pronotum  and  elytra  green  or  yellowish,  the  latter  with  twelve  black 
spots  often  partly  fused.  Control  thus  far  has  been  directed  mainly  against  the 
beetles,  spraying  plants  on  which  they  are  feeding  with  arsenate  of  lead  (neutral) 
at  the  standard  formula,  using  either  water  or  Bordeaux  mixture. 


FIG.  113. — Adult  Flea  Beetles:  a,  Spinach  Flea  Beetle,  enlarged  nearly  five  times; 
6,  Potato  Flea  Beetle,  enlarged  about  seven  times;  c,  Egg-plant  Flea  Beetle,  enlarged  about 
seven  times.  (From  U.  S.  D.  A.  Bulletins.) 

Flea  Beetles. — Many  tiny  beetles  belonging  in  the  Chrysomelidse 
are  known  as  Flea  beetles  because  when  disturbed  they  hop  away  like 
fleas.  The  economic  forms  vary  in  size  from  about  a  fifth  to  a  fifteenth 
of  an  inch  in  length  (Fig.  113).  Most  of  them  are  blackish  or  steel- 
blue,  though  some  have  portions  of  the  body  yellow,  whitish,  red  or 
other  colors.  The  hind  femora  are  very  large,  enabling  the  insects  to  make 
vigorous  leaps.  The  adults  feed  on  the  leaves,  eating  tiny  holes,  while  in 
most  cases  the  Iarva3  are  root  feeders,  generally  on  the  same  plants  which 
their  adults  attack,  though  in  some  cases  they  also  attack  the  leaves. 
Many  attack  garden  crops  such  as  the  potato,  turnip,  beet,  spinach, 
rhubarb  and  radish,  while  other  species  feed  on  the  strawberry,  grape, 
tobacco,  hop,  clover,  apple,  Virginia  creeper,  willow,  alder,  etc.  In  most 
cases  there  are  two  generations  a  year,  the  first  appearing  early  in  the 
season  and  the  second  in  mid-summer  or  early  fall,  though  some  species 
have  but  one  generation  and  some  have  several. 

Control. — These  insects  which  are  often  serious  pests,  appear  to  be 
repelled  by  Bordeaux  mixture,  but  it  is  better  to  combine  this  with 


THE  COLEOPTERA 


123 


arsenate  of  lead,  standard  formula.  Dusting  with  Paris  green  and  land 
plaster  may  also  be  used  with  some  success  as  a  control  method.  Where 
the  larvae  mine  in  the  leaves,  as  certain  species  do  to  some  extent,  treat- 
ment must  be  directed  toward  the  destruction  of  the  adults  which  indeed, 
should  be  the  case  with  all  the  species.  Where  plants  are  started  in  seed 
beds  and  are  attacked  there,  screening  the  beds  with  cheese-cloth  is 
practicable.  When  plants  from  seed  beds  are  set  out  they  may  be  pro- 
tected by  dipping  them  in  1  Ib.  of  arsenate  of  lead  paste  in  10  gal.  of 
water  before  setting  them. 

It  is  believed  that  the  Cucumber  Flea-beetle  like  the  Three-lined 
Cucumber  Beetle  may  inoculate  plants  with  the  cucurbit  wilt  already 
referred  to.  Certainly  the  tiny  holes  made  in  the  leaves  by  their  feeding 
provide  excellent  places  for  the  spores  of  fungi  to  establish  themselves 
and  produce  disease. 

The  Common  Asparagus  Beetle  (Crioceris  asparagi  L.). — This  insect 
reached  this  country  from  Europe  about  1856  and  is  now  present  in  the 
Eastern  States  as  far  south  as  North  Carolina  and  westward  to  the  Mis- 
sissippi River.  Farther  west  it  has  been  reported  from  several  scattered 
localities,  including  California,  and  it  may  be  assumed  that  it  will  in 
time  become  generally  distributed. 


FIG.  114. — Common  Asparagus  beetle  (Crioceris  asparagi  L.) :  a,  Adult;  b,  Egg;  c, 
larva,  just  hatched;  d,  full-grown  larva.  Greatly  enlarged:  hair  lines  beside  a  and  b  show 
real  length.  (From  U.  S.  D.  A.  Farm.  Bull.  837.) 

The  adult  beetle  (Fig.  114)  is  a  little  less  than  a  quarter  of  an  inch 
long.  It  is  dark  blue  or  bluish  black,  with  a  red  thorax,  and  its  elytra 
are  dark  blue  and  yellow,  the  former  present  as  a  band  along  the  middle, 
with  two  lateral  extensions  toward  the  sides  into  the  yellow,  while  the 
outer  border  is  reddish.  The  distribution  and  amount  of  the  blue  and 
yellow  varies  considerably  according  to  the  locality,  the  blue  often  so 
encroaching  on  the  yellow  as  to  leave  only  six  spots  of  the  latter  color. 

The  insect  winters  in  the  beetle  stage  in  any  protected  place  it  can 
find,  and  as  the  asparagus  plants  begin  to  come  up  in  spring,  leaves  its 
winter  quarters  to  feed  and  lay  its  eggs  (Fig.  115a).  The  beetles  at  this 


124 


APPLIED  ENTOMOLOGY 


time  feed  on  the  stems  and  when  abundant  do  considerable  harm.  The 
eggs  are  laid  on  the  stems,  singly,  attached  by  one  end,  are  dark  brown 
in  color,  and  hatch  in  from  3  to  8  days  according  to  the  temperature. 
The  grubs  (Fig.  114d),  often  called  " slugs"  are  gray  with  black  heads. 
They  feed  from  10  days  to  2  weeks,  gnawing  the  stems  and  thus  aid  the 
beetles  in  making  these  unfit  for  sale.  Then  they  enter  the  ground  and 
pupate  for  about  a  week  which  is  followed  by  the  emergence  of  the  adults. 
The  life  cycle  therefore  is  from  about  4  weeks  during  hot  weather  to  6  or 

7  weeks  in  spring  or  fall.  There  are 
at  least  two  generations  in  the  North 
and  probably  three  or  four  in  the 
South  each  year. 

The  later  generations  feed  on 
the  leafy  growth  and  in  the  case  of 
young  plants  may  seriously  weaken 
them.  Eggs  when  abundant  on  the 
stems  cut  for  market  are  objection- 
able, and  a  black  fluid  poured  out  by 
the  grubs  when  disturbed,  often  stains 
the  stems  also.  Fortunately,  exces- 
sive heat  appears  to  kill  many  of  the 
grubs,  and  the  alternation  of  severe 
cold  with  much  warmer  periods  in 
winter,  has  a  similar  effect  on  hiber- 
nating adults.  Several  parasites  and 
other  enemies  also  reduce  the  numbers 
of  this  pest. 

Control. — Fresh  air-slaked  lime 
dusted  over  the  plants  while  these 
are  wet  with  dew  is  an  excellent  con- 
trol measure  for  small  areas.  Fowls 

feed  freely  on  the  insects  and  are  therefore  of  value  when  allowed  to  run 
through  the  asparagus  beds.  For  larger  areas  a  frequent  practice  is  to 
keep  the  plants  as  closely  cut  as  possible,  leaving  a  few  stems  here  and 
there  as  traps  on  which  the  beetles  can  lay  their  eggs.  These  plants 
should  be  cut  once  a  week  and  destroyed,  others  being  then  allowed  to 
grow  to  take  their  places.  Where  cutting  is  not  being  done,  spraying 
with  arsenate  of  lead  a  little  stronger  than  the  standard  formula  is  a 
very  satisfactory  treatment,  the  number  of  treatments  required  being 
generally  not  more  than  two  or  three  at  most  during  an  entire  summer. 

The  Twelve-spotted  Asparagus  Beetle  (Crioceris  duodecimpunctata  L.). — 
This  insect  arrived  in  this  country  from  Europe  about  1881  and  was  first  dis- 
covered near  Baltimore,  Md.  Though  beginning  its  work  here  more  than  20 
years  later  than  the  other  species,  it  has  already  nearly  everywhere  overtaken  the 
latter  and  is  now  widely  distributed. 


FIG.  115. — Eggs,  larvae  and  adults  of 
Common  Asparagus  Beetle  on  the  plant. 
Natural  size.  (From  U.  S.  D.  A.  Farm. 
Bull.  837.) 


THE  COLEOPTERA 


125 


The  adult  beetle  (Fig.  116)  is  slightly  larger  and  broader  in  proportion  to 
its  length  than  the  Common  Asparagus  Beetle.  It  is  orange-red  or  brick-red 
above  except  for  twelve  black  dots  on  the  elytra.  The  life  history  and  habits 
do  not  seem  to  differ  much  from  those  of  the  other  species  except  in  the  follow- 
ing features.  The  beetle  appears  to  depend  upon  flight  rather  than  upon  dodg- 
ing around  the  stems  to  escape  its  enemies:  the  egg  is  not  attached  by  one 
end  but  by  a  side,  to  the  plant;  the  larva  feeds  inside  the  berries  and  is  orange 
to  yellowish  in  color.  The  hibernating  insects  feed  on  the  young  plants  like  the 
other  species  but  the  beetles  of  later  generations  feed  on  the  berries.  Control  is 

similar  to  that  for  the  Common  Asparagus  Beetle 

except  that  dusting  with  air-slaked  lime  will  not 

reach  the  larvae. 

The  Grape-root  Worm  (Fidia  viticida  Walsh). 

• — The   Grape-root   Worm  appears  to  be  a  native 


IF*-  ^T-^-i  ^K-  m 

m 


FIG.  116.  FIG.  117. 

FIG.  116. — Adult  Twelve-spotted  Asparagus  Beetle  (Crioceris  duodecimpunctata 
L.)  nearly  six  times  natural  size.  (From  U.  S.  D.  A.  Farm.  Bull.  837.) 

FIG.  117. — Adult  Grape-root  Worm  (Fidia  viticida  Walsh),  about  natural  size,  and 
its  work  on  a  grape  leaf.  (Modified  from  Cornell  Exp.  Sta.  Bull.  208.) 

of  this  country  and  is  found  from  New  York  to  North  Carolina  (and 
Florida?)  and  west  to  Dakota,  Missouri  and  Texas.  There  is  also  a  California 
record  for  it  but  it  appears  to  be  largely  replaced  there,  by  the  California 
Grape-root  worm  (Bromius  obscurus  L.).  The  insect  passes  the  winter  as 
the  nearly-  or  full-grown  larva,  a  number  of  inches  deep  in  the  ground,  but  in 
spring  it  comes  nearer  the  surface  and  feeds  on  the  roots  of  the  grape  until  full 
grown.  Pupation  usually  occurs  two  or  three  inches  below  the  surface  and  the 
adult  beetles  begin  to  emerge  about  the  time  blossoming  of  the  grape  ends,  most 
of  them  appearing  during  a  period  of  4  or  5  weeks.  The  beetles  (Fig.  117)  are 
brown,  covered  with  whitish  hairs;  are  rather  stout,  about  a  quarter  of  an  inch 
long  and  have  long  legs.  They  feed  on  the  grape  leaves,  making  irregular  holes, 
often  so  connected  as  to  form  narrow,  crooked  slits.  The  eggs  are  laid,  several 
hundred  in  all,  placed  in  clusters  of  about  30  or  40,  mainly  under  loose  strips 
of  bark.  These  hatch  in  about  10  days  and  the  tiny  grubs  drop  to  the  ground 
and  work  down  to  the  roots  consuming  the  smaller  ones  entirely  and  burrowing 
in  the  larger  ones,  until  winter,  when  they  are  full  grown  or  nearly  so. 

When  these  insects  are  abundant  the  grape  vines  may  be  killed  in  a  year  or 
two  but  the  usual  result  of  their  presence  is  to  so  check  the  growth  of  the  plants 
that  little  or  no  crop  is  obtained.  The  grape-raising  territory  of  western  New 
York,  Pennsylvania  and  Ohio  appears  to  suffer  most  from  the  attacks  of  this  pest. 


126  APPLIED  ENTOMOLOGY 

Control. — The  adult  beetles  can  be  killed  by  spraying  the  leaves  with  arsenate 
of  lead  using  3  or  4  Ib.  of  the  paste  in  50  gal.  of  Bordeaux  mixture,  just  before 
or  as  soon  as  the  first  signs  of  feeding  appear,  and  again  after  10  days.  Great 
care  must  be  taken,  however,  to  do  this  work  thoroughly,  as  the  beetles  avoid 
sprayed  foliage.  The  beetles  may  also  be  jarred  off  the  vines,  particularly  on 
warm  days,  onto  sticky  boards,  fly  paper,  or  sheets  or  some  other  type  of  catcher 
placed  beneath  the  plants,  whence  they  can  be  gathered  and  destroyed.  The 
pupae  are  located  within  a  few  inches  of  the  top  of  the  ground  and  are  mostly 
within  two  or  three  feet  of  the  vine.  In  this  state  of  their  existence  they  are  easily 
destroyed  by  any  thorough  breaking  up  of  the  soil  where  they  are,  and  this  is 
taken  advantage  of  by  throwing  up  the  earth  on  each  side  of  the  vines  in  the  fall 
to  form  a  ridge.  Most  of  the  larvse  work  up  into  this  to  pupate,  the  following 
spring,  and  while  the  insects  are  in  the  pupa  stage  there  this  ridge  should  be  hoed 
away  by  a  horse-hoe  and  by  hand,  or  by  the  latter  alone  for  small  areas.  Later 
cultivation  will  reach  some  of  those  escaping  the  first  treatment  which  in  the 
grape  belt  named  is  usually  about  the  middle  of  June. 

The  Calif ornian  species  is  a  little  smaller  than  the  one  just  described,  and  jet- 
black  or  brown.  Its  habits  and  methods  for  controlling  it  are  .about  the  same  as 
with  the  eastern  pest. 

The  Elm  Leaf  Beetle  (Galerucella  luteola  Muls.). — This  European  insect 
appears  to  have  reached  this  country  at  Baltimore  about  1834  and  has  now  spread 
through  most  of  the  New  England  and  Middle  Atlantic  States  and  westward 
nearly  to  the  Mississippi  River,  though  not  everywhere  present  within  these 
limits. 

The  adult  beetle  (Fig.  118)  is  about  a  quarter  of  an  inch  long,  dull  yellow  in 
color,  with  black  spots  on  the  head  and  pronotum,  a  black  band  near  the  outside 
of  each  elytron,  and  a  short  streak  at  the  base  of  each,  nearer  the  middle.  The 
beetles  winter  over  in  protected  places  and  in  the  spring  the  dull  yellow  has 
changed  to  an  olive-green  (Fig.  118).  They  fly  to  the  elm  trees  when  the  foliage 
develops,  and  feed,  eating  irregular  holes  in  the  leaves  and  from  time  to  time  lay- 
ing yellow  eggs  on  the  underside  of  the  leaves,  usually  about  25  in  number  and 
nearly  always  in  two  rows,  side  by  side  (Fig.  118).  The  eggs  hatch  after  about  a 
week  and  the  tiny  yellow  and  black  grubs  feed  for  about  3  weeks,  working  on  the 
under  surface  and  leaving  the  upper  epidermis  of  the  leaf  unbroken.  When  full- 
grown  (Fig.  118)  and  about  half  an  inch  long  they  crawl  down  the  tree  to  the 
trunk  and  pupate  for  from  1  to  over  3  weeks  according  to  the  temperature,  either  in 
crevices  of  the  bark  on  the  lower  part  of  the  trunk  or  on  the  ground  near  the  foot 
of  the  tree  (Fig.  118).  In  the  more  northerly  states  the  larvss  feed  during  June. 
Farther  south  they  begin  in  May  and  a  second  generation  feeds  during  the  late 
summer  or  early  fall.  The  European  elms  are  most  severely  injured  by  this 
insect  but  other  species  often  suffer  greatly. 

Control. — Spraying  the  trees  about  the  time  the  eggs  are  laid,  i.e.,  soon  after 
the  leaves  are  fully  grown,  with  arsenate  of  lead  is  the  usual  method  of  control. 
The  strength  of  the  material  should  be  increased  above  the  standard  to  5  Ib.  of  the 
paste,  to  obtain  good  results,  and  it  should  be  kept  in  mind  that  as  the  grubs  do 
not  feed  on  nor  reach  the  upper  surface  of  the  leaves,  the  spray  should  be  directed 
as  far  as  possible  onto  the  under  surfaces. 


THE  COLEOPTERA 


127 


t,  M,  Jotitel,   1900, 


FIG.  118. — The  Elm  Leaf  Beetle  (Galerucella  luteola  Muls.) :  1,  egg  cluster;  la,  single  egg 
greatly  enlarged;  2,  recently  hatched  larva  (grub);  3,  full-grown  larva;  4,  pupa;  5, 
beetles  after  wintering  over;  6,  freshly  emerged  beetles;  7,  under  surface  of  leaf  showing 
grubs,  their  work  and  a  few  holes  eaten  by  adult  beetles;  8,  leaf  nearly  skeletonized  by  the 
larvae;  9,  leaf  eaten  by  adults.  Hair  lines  by  Figs.  1  to  6  show  natural  size:  7,  8  and  9 
natural  size.  (From  Bull.  332  Ohio  Agr.  Exp.  Sla.  After  Felt.) 


128 


APPLIED  ENTOMOLOGY 


Destroying  the  descending  larvae  and  the  pupse  on  the  lower  part  of  the  trunk 
and  on  the  ground,  with  a  strong  kerosene  emulsion  spray  is  an  auxiliary  treat- 
ment, but  as  these  individuals  have  completed  their  feeding,  this  affects  only  the 
abundance  of  the  next  generation.  Power  sprayers  are  a  necessity  for  spraying 
tall  trees  in  the  way  here  described. 

The  Tortoise  Beetles  are  interesting  members  of  the  Chrysomelidse 
(Fig.  119)  because  of  their  resemblance  in  form  to  tortoises  and  inmost 
cases,  on  account  of  their  golden  color,  which  is 
lost  after  death.  Some  species  attack  the  sweet 
potato  but  are  not  usually  serious  pests.  They  are 
small  insects,  usually  not  over  a  quarter  of  an  inch 
long,  nearly  as  wide,  and  often  with  black  mark- 
ings. If  they  become  injuriously  abundant,  spray- 
ing the  leaves  on  which  the  larvae  feed,  with  arsenate 
of  lead  will  control  them. 

Family  Bruchidae  (Pea  and  Bean  Weevils). — In 

FIG.    119. — Tortoise          .  ..  .  . 

Beetle  (Deioyala  davata  this  group  of  small  beetles  the  head  is  extended 
Fab.)  about  2^  times  downward  into  a  broad  but  short  snout.  The 

natural  size.    (Original.)  ,1111  ,,      ,  -      i 

elytra  are  snorter  than  the  body  leaving  the  hinder 

end  of  the  abdomen  exposed  above.  The  larvae  feed  in  the  seeds  of 
leguminous  plants  such  as  peas  and  beans,  and  frequently  cause  a  great 
amount  of  damage.  Several  kinds  are  abundant  in  the  United  States, 
the  pea  weevil  and  the  common  bean  weevil  being  perhaps  the  most 
important. 

The  Pea  Weevil  (Bruchus  pisorum  L.) . — This  pest  of  field  and  garden 
peas  winters  as  the  adult  beetle  (Fig.  120a)  either  in  peas  or  in  protected 
places,  and  after  the  pea  pods 
begin  to  form,  lays  its  eggs  on 
them.  It  is  about  one-fifth  of 
an  inch  long,  brownish,  with 
black  and  white  spots.  The 
larvae  (Fig.  1206)  bore  their  way 
into  the  peas,  the  holes  they 
make  either  closing  up  or  being 
too  small  to  be  noticed,  and  feed 
on  the  contents  of  the  pea  until 
full-grown.  They  then  pupate 
(Fig.  120c)  and  upon  the  pro- 
duction of  the  adult,  those  in  the  South  leave  the  peas,  while  in  the 
North  they  remain  in  them  over  winter.  Only  one  weevil  usually  feeds 
in  a  pea  and  the  insect  cannot  reproduce  in  dried  peas.  There  is  there- 
fore only  one  generation  a  year  except  where  spring  and  fall  crops  of  peas 
are  grown. 


FIG.  120. — Pea  Weevil  (Bruchus  pisorum  L.) : 
a,  adult  beetle;  b,  larva  (grub);  c,  pupa. 
Greatly  enlarged.  (From  U.  S.  D.  A.  Farm. 
Bull.  983.) 


THE  COLEOPTERA  129 

The  Common  Bean  Weevil  (Bruchus  obtectus  Say). — This  insect  is 
now  found  in  nearly  all  parts  of  the  world.  The  beetle  is  smaller  than 
the  Pea  Weevil  and  is  brownish-gray  in  color,  its  elytra  slightly  mottled 
(Fig.  ]  21).  The  beetle  lays  its  eggs  on  or  in  the  pods  of  the  beans  growing 
in  the  field,  either  in  holes  made,  or  in  cracks  caused  by  the  pods  splitting. 
In  the  case  of  shelled  beans  the  eggs  are  placed  on  the  beans  themselves. 
The  larvae  gnaw  their  way  to  and  into  the  beans,  and  unlike  the  Pea  Weevil, 
a  number  may  enter  the  same  seed  and  feed  upon  its  substance.  Devel- 
opment from  the  egg  to  the  adult  occurs  within  the  bean  and  the  adult 
finally  escapes  through  a  circular  hole  it  has  cut  in  the  skin  after  having 
spent  from  3  weeks  to  nearly  3  months  there,  according  to  the  tempera- 
ture where  the  beans  are  kept.  When  infested 
beans  gathered  in  the  field  are  brought  in,  their 
infestation  may  not  be  apparent,  but  after 
being  kept  a  while,  the  adult  beetles  will  escape 


FIG.  121.  FIG.  122. 

FIG.   121. — Adult  Common  Bean  Weevil  (Bruchus    obtectus    Say),    greatly    enlarged: 
hair  line  at  right  shows  real  length.     (From  U.  S.  D.  A.  Farm.  Bull.  983.) 
FIG.  122. — Work  of  Bean  Weevils,  natural  size.     (Original.) 

and  lay  their  eggs  for  another  generation  which  will  develop  in  the  same 
seeds  if  these  are  kept  where  it  is  fairly  warm  (Fig.  122),  and  thus  by 
spring  there  may  be  practically  no  beans  left  to  plant.  Six  generations 
may  be  produced  in  a  year  in  the  South  and  if  the  beans  are  kept  where 
it  is  warm  during  the  colder  months,  as  many  may  occur  in  northern 
localities,  though  in  the  field  it  is  doubtful  if  there  are  more  than  one 
or  two. 

Another  species,  the  Cowpea  Weevil  (Bruchus  chinensis  L.)  which  feeds 
on  the  cowpea,  and  other  peas,  and  beans,  is  more  abundant  in  the  South,  and  a 
fourth,  the  Four-spotted  Bean  or  Cowpea  Weevil  (Bruchus  quadrimaculatus  Fab.) 
has  a  wide  distribution,  probably  wherever  cowpeas  are  grown.  Both  of  these 
species  breed  generation  after  generation  in  stored  cowpeas,  and  in  warm 
temperatures  there  may  be  a  number  of  generations  each  year. 

The  Broad  Bean  Weevil  (Bruchus  rufimanus  Boh.)  in  its  life  and  habits  more 
nearly  resembles  the  Pea  Weevil  than  the  other  species  above  considered.  It  is 
injurious  in  Europe  and  Northern  Africa  and  has  now  established  itself  in  Cali- 
fornia. The  beetles  resemble  the  Pea  Weevil  but  seem  to  prefer  broad  beans  or 
horse  beans.  They  appear  in  the  fields  in  March  and  lay  numbers  of  eggs  on  the 
bean  pods  and  the  grubs  on  hatching  make  their  way  to  the  young  beans,  several 


130  APPLIED  ENTOMOLOGY 

often  entering  one  bean.  Feeding  is  completed  by  early  August  and  the  adults 
are  produced  later  in  the  fall.  They  generally  winter  in  the  beans  but  do  not 
breed  in  dried  beans,  there  being  therefore  only  one  generation  a  year. 

Injuries. — The  damage  caused  by  the  attacks  of  pea  and  bean  weevils 
is  of  two.  kinds:  injury  by  consuming  the  bulk  of  the  seed  and  leaving  the 
remainder  unfit  for  food;  and  injury  by  so  reducing  the  stored  material 
or  the  germ  itself  that  the  seed  cannot  germinate  and  grow. 

Control  of  Pea  and  Bean  Weevils. — The  original  attacks  of  these  in- 
sects are  upon  growing  plants  out-of-doors.  Here  no  control  seems  pos- 
sible. When  the  crop  is  gathered,  however,  treatment  can  easily  be 
given  by  shelling  at  once,  placing  the  seed  in  gas-tight  receptacles,  and 
fumigating  it  with  carbon  disulfid,  using  this  at  the  rate  of  at  least  8  or 
10  Ib.  for  every  1,000  cu.  ft.  of  space  in  the  container,  and  continuing  the 
treatment  for  at  least  1 — better  2 — days.  The  disulfid  may  be  poured  di- 
rectly onto  the  top  of  the  seeds.  For  best  results  this  should  be  done  in  a 
place  where  the  temperature  is  at  least  75°F.  Then  the  seed  should  be 
packed  in  weevil-tight  boxes,  but  it  would  be  wise  to  examine  it  again 
after  a  time  and  if  living  weevils  are  still  present,  give  it  another  treat- 
ment. Where  the  seed  is  not  to  be  used  for  food,  packing  it  in  air-slaked 
lime  at  the  rate  of  1  part  by  weight  of  lime  to  2  or  3  parts  by  weight  of 
seed  has  proved  satisfactory.  Even  where  use  as  food  is  intended,  this 
method  can  be  used  if  the  seed  is  thoroughly  washed  before  cooking. 
Cold  storage  below  34°F.  will  prevent  development  of  the  insects.  Heat 
will  destroy  the  weevils  and  if  seed  is  raised  to  131°F.  and  kept  at  that 
temperature  for  an  hour,  this  will  kill  all  the  weevils  present.  Appar- 
ently, treatment  in  this  way  and  for  this  length  of  time  will  not  prevent 
germination.  None  of  these  methods  will  prevent  reinfestation  if  the 
seeds  are  afterwards  exposed  to  attack  by  insects  from  outside,  where 
the  temperature  is  such  that  they  are  active.  In  general  then,  give  the 
first  treatment  immediately  after  gathering,  and  store  in  tight  containers 
and  preferably  in  a  cold  place. 

The  shorter  seasons  and  cold  winters  of  the  North  give  the  pea  and 
bean  weevils  less  opportunity  to  increase  through  a  number  of  generations 
than  in  the  South,  and  many  of  the  adults  are  killed  by  the  cold.  North- 
ern climates  for  these  reasons  are  therefore  better  for  the  extensive  pro- 
duction of  seeds  of  these  plants. 

Family  Cerambycidae  (Round-headed  Borers  or  Longicorn  Beetles).— 
The  insects  of  this  family  are  for  the  most  part  of  fair  size,  a  number  being 
several  inches  in  length.  Their  antennae  are  usually  long — sometimes 
longer  than  the  body — and  the  beetles  are  frequently  bright-colored  and 
strikingly  marked  (Fig.  123). 

The  larvae  are  chiefly  wood-borers,  living  in  burrows  in  the  trunks  or 
roots  of  trees,  or  the  pith  of  plant  stems,  and  are  termed  round-headed 


THE  COLEOPTERA 


131 


borers  because  the  thoracic  segments  are  circular  in  outline  and  the 
tunnels  they  produce  are  therefore  also  of  this  shape.  The  larvae  them- 
selves are  soft,  whitish  or  yellowish  grubs,  with  strong  jaws,  and  most  of 
them  have  no  legs.  The  eggs  are  usually  laid  on  the  bark  of  the  tree  and 
the  larvae  live  on  the  wood  they  tunnel  out,  for  a  varying  period,  usually 
2  or  3  years,  and  pupate  in  the  tunnels  just  beneath  the  bark, 
through  which  the  emerging  beetle  finally  gnaws  its  way  and  escapes. 


FIG.  123. — Cerambycid  (Monohammus),  natural  size,  showing  long  antennae.     (Original.) 

Some  species  cut  the  stem  in  which  they  live,  nearly  through,  and  when 
it  breaks  off,  fall  with  it  to  the  ground,  thus  pruning  the  tree.  Those 
which  tunnel  in  the  heart-wood  of  timber  trees  often  greatly  reduce  the 
value  of  the  timber  by  their  holes.  Some  species  attack  sound  wood  and 
apparently  vigorous  trees,  while  others  seem  to  prefer  trees  already  un- 
healthy, for  their  food.  The  family  is  a  large  one  and  contains  many 
forms  injurious  to  shade  and  forest  trees. 

The  Round-headed  Apple-tree  Borer  (Saperda  Candida  Fab.). — This 
serious  enemy  of  the  apple  tree  is  found  practically  everywhere  in  the 
eastern  United  States  except  in  the  extreme  South,  and  westward  into 
Minnesota,  Iowa,  New  Mexico  and  Texas.  It  also  attacks  the  service 
tree,  pear,  quince,  thorns,  mountain  ash,  and  a  few  other  Rosaceae.  The 
adult  beetle  (Fig.  124)  is  a  little  less  than  an  inch  long,  pale  brown  above, 
with  a  pair  of  white  stripes  extending  backward  from  the  head  across 
the  pronotum  and  along  the  elytra  to  their  tips  at  the  hinder  end  of  the 
body.  Beneath,  it  is  silvery  white.  It  appears  during  the  late  spring 
and  summer  months  and  lays  its  eggs  singly  here  and  there  in  small  slits 
it  cuts  in  the  bark  near  the  base  of  the  tree,  laying  about  15  to  30  in  all. 
On  hatching,  2  to  3  weeks  later,  the  larva  burrows  through  the  bark  to 
the  sap-wood,  and  there  makes  broad,  rather  shallow  galleries  just  under 
the  bark  and  in  general  working  downward.  The  bark  over  these  gal- 
leries frequently  dries  and  cracks,  or  the  borer  makes  holes  in  it,  letting 


132 


APPLIED  ENTOMOLOGY 


out  the  borings  and  castings,  often  called  " sawdust"  which  shows  the 
location  of  the  burrows.  After  hibernating  during  the  winter  the  borer 
(Fig.  124)  resumes  its  work  the  following  spring,  still  feeding  on  the  sap- 
wood,  and  if  the  tree  is  small  or  if  several  borers  are  present,  girdling  may 
result.  After  a  second  winter  in  hibernation  the  borer  turns  its  atten- 
tion to  the  heart-wood,  boring  into  this,  and  finally  as  it  approaches  full 
growth,  working  its  way  out  toward  the  surface,  being  now  about  three- 
quarters  of  an  inch  long.  After  a  third  winter  of  rest  the  larva  pupates 
in  its  tunnel  in  the  spring,  having  previously  carried  the  tunnel  out  to  the 
bark,  and  the  adult  beetle  emerges  after  about  3  weeks.  One  generation 


FIG.  124. — Round-headed  Apple-tree  Borer  (Saperda  Candida  Fab.):  back  and  side 
views  of  adult  beetle  on  bark  and  exit  hole;  full-grown  larvse  (borers).  (After  Rumsey 
and  Brooks.) 

accordingly  requires  3  years  in  which  to  complete  its  life  history  but 
this  comes  in  parts  of  4  calendar  years.  In  the  southern  part  of  its 
range  this  is  shortened  to  2  years  and  in  intermediate  regions  some  may 
require  2,  and  some  3  years. 

Small  trees  suffer  most  severely  by  the  attacks  of  this  pest,  a  single 
borer  often  entirely  girdling  a  tree :  larger  ones  are  weakened  and  become 
unhealthy  and  if  strongly  infested  may  also  be  killed. 

Control. — Various  methods  of  control  have  some  value.  "  Worming" 
the  trees,  i.e.,  cutting  out  the  young  borers  early  in  the  fall  is  a  good 
practice  if  it  is  thoroughly  done  and  if  the  cutting  is  carried  on  carefully. 
Litter  should  be  carefully  scraped  away  from  the  trunk  to  expose  any 
sawdust  present,  and  from  this  the  burrows  can  be  located  and  the  dead 
bark  cut  out  and  the  borer  killed,  either  in  place  under  the  bark  or  by 
running  a  flexible  wire  into  its  burrow  if  it  has  gone  deeper  into  the  tree. 
In  cases  where  the  borer  cannot  be  reached  by  the  wire,  a  little  carbon 


THE  COLEOPTERA  133 

disulfid  on  cotton  placed  in  the  burrow,  the  opening  then  being  closed 
with  mud,  will  serve  the  same  purpose.  Worming  should  be  done  in 
early  fall;  the  work  should  be  thorough,  and  host  trees  of  every  kind 
within  several  hundred  feet  of  the  orchard  should  be  worked  at  the 
same  time  for  the  beetles  do  not  usually  fly  far  and  if  the  immediate 
neighborhood  is  cleared  of  them,  reinfestation  from  a  distance  does  not 
occur  very  frequently. 

Thick  paints  are  sometimes  used  as  repellents.  These  are  applied 
beginning  a  few  inches  below  ground,  the  earth  being  removed  for  the 
purpose,  and  extending  about  a  foot  up  the  trunk,  just  before  the  egg- 
laying  period  begins.  The  paint  should  be  thick  and  be  thoroughly 
applied  and  should  be  pure  white  lead  in  raw  linseed  oil,  as  other  materials 
have  been  known  to  injure  the  trees. 

Protectors,  such  as  newspaper  wrappings  (several  layers  thick), 
building  paper,  cloth,  wire  netting,  etc.,  may  be  used,  being  placed  around 
the  trunks  before  egg-laying  begins.  In  all  cases,  however,  these  must 
enter  the  ground  at  the  bottom  and  be  tightly  fitted  around  the  trunk 
at  the  top  and  be  without  holes  or  cracks  through  which  the  beetle  can 
crawl.  Asphaltum  has  given  fair  results  in  some  cases,  but  appears  to 
be  liable  to  injure  the  tree. 

As  the  beetle  feeds  somewhat  on  twigs  and  leaves,  the  usual  sprayings 
with  a  stomach  poison  for  other  apple  pests  are  liable  to  kill  some  of  the 
beetles  also.  Woodpeckers  feed  freely  on  the  borers. 

Family  Coccinellidae  (Lady  Beetles,  Lady  Bugs  or  Lady  Birds). — 
The  lady  beetles  are  nearly  all  carnivorous,  feeding  both  as  larvae  and 
adults  on  scale  insects,  plant  lice  and  other  important  pests.  They  are 
generally  small  beetles,  nearly  circular  or  oval  in  outline,  strongly  convex, 
often  resembling  in  size  and  form  a  split  pea.  Their  colors  are  usually 
black  and  red  or  reddish-yellow,  sometimes  the  spots  or  markings  being 
black  on  a  red  ground,  sometimes  the  reverse.  In  a  number  of  species 
the  beetle  is  entirely  black  (Figs.  125  and  126). 

The  larvae  (Fig.  126)  are  active  and  crawl  around  over  leaves,  twigs, 
etc.,  searching  for  their  food.  They  are  dark  colored,  but  frequently 
have  a  few  spots  of  yellow  or  blue  on  the  side  of  the  body,  and  their 
general  appearance  has  suggested  to  some  persons,  a  resemblance  to 
alligators. 

The  family  is  quite  a  large  one,  and  its  species  are  abundant  and  well 
distributed  over  this  country.  Among  the  more  useful  or  noticeable  of 
the  family  is  the  Two-spotted  Lady  beetle  (Adalia  bipunctata  L.),  one  of 
the  smaller  species  averaging  about  a  sixth  of  an  inch  in  length  (Fig.  1256). 
The  head  is  black,  sometimes  with  two  yellow  spots;  the  pronotum  black 
with  yellow  side  margins,  and  the  elytra  are  red  with  a  black  dot  in  the 
center  of  each.  This  insect  frequently  winters  in  houses  and  may  be  found 
on  the  windows  in  spring  trying  to  escape.  It  is  often  mistaken  for  some 


134 


APPLIED  ENTOMOLOGY 


injurious  household  pest  on  this  account.  This  species  feeds  mainly  on 
plant  lice,  but  to  some  extent  also  on  the  pear  psylla.  Another  species  of 
about  the  same  size  is  known  as  the  Twice-stabbed  Lady  beetle  (Chilo- 
corus  bivulnerus  Muls.).  Here  the  head  and  pronotum  are  black,  as  are 
also  the  elytra,  except  for  a  red  spot  in  the  center  of  each,  thus  just 
reversing  the  elytral  color  pattern  of  the  last  described  species.  It  feeds 
on  scale  insects  and  also  on  plant  lice  and  the  Colorado  Potato  Beetle. 


FIG.  125. — Examples  of  Lady  Beetles:  a,  Twice-stabbed  Lady  Beetle  (Chilocorus 
bivulnerus  Muls.) :  b,  Two-spotted  Lady  Beetle  (Adalia  bipunctata  L.) ;  c,  Nine-spotted 
LadyBeetle  (Coccinellanovem,notata  Hbst.) :  d,  Spotted  Lady  Beetle  (Coleomegilla  fuscilabris 
Mu)s.):  all  about  twice  natural  size.  (From  Conn.  Agr.  Exp.  Sta.  Bull.  181.) 

Other  common  species  are  the  Nine-spotted  Lady  beetle  (Coccinella  9-notata 
Herbst.)  with  nine  black  spots  on  its  red  elytra;  the  Fifteen-spotted  Lady  beetle 
(Anatis  15-punctata  Oliv.),  the  largest  species  in  the  Northeastern  States,  which 
has  15  black  spots  on  its  red  elytra;  the  Pitiful  Lady  beetle  (Pentilia  misella  Lee.), 
a  very  tiny  black  species  which  feeds  on  scale  insects  and  aphids,  and  the  Spotted 
Lady  beetle  (Coleomegilla  fuscilabris  Muls.)  about  a  fifth  of  an  inch  long,  usually 
bright  pink  with  black  spots  and  with  its  body  rather  oval  in  outline,  somewhat 
pointed  behind.  This  species  feeds  on  many  kinds  of  plant  lice  and  other  small 
insects  and  tends  to  hibernate  in  clusters,  often  several  hundred  together,  under 
leaves  at  the  bases  of  treetrunks. 


FIG.  126. — Different  stages  of  the  Nine-spotted  Lady  Beetle:  a,  adult;  b,  larva;  c,  pupa; 
d,  eggs.     All  much  enlarged.     (Modified  from  Palmer,  Ann.  Ent.  SQC.  Am.,  vii,  1914.) 

The  Convergent  Lady  beetle  (Hippodamia  convergens  Guer.)  is  about 
a  quarter  of  an  inch  long,  with  two  converging  yellow  marks  on  the 
pronotum  and  six  black  spots  on  each  elytron.  This  widely  distributed 
species  has  been  found  feeding  on  a  number  of  kinds  of  plant  lice  and  in 
addition,  on  asparagus  beetle  larvae,  eggs  of  the  Colorado  Potato  beetle 
and  of  the  Grape-root  worm,  red  spiders,  the  Bean  Thrips,  Alfalfa  Weevil 
and  Chinch  Bug.  On  the  Pacific  Coast  it  gathers  in  enormous  numbers 


THE  COLEOPTERA  135 

in  the  high  mountains  to  hibernate  and  while  thus  collected  in  quantities 
they  are  gathered  and  in  spring  distiibuted  through  the  truck-growing 
regions  to  attack  the  plant  lice,  about  30,000  being  regarded  as  enough  to 
protect  the  plants  growing  on  10  acres.  Several  tons  are  often  collected 
for  distribution  for  this  purpose.  It  takes  nearly  1,500  of  these  beetles 
to  weigh  an  ounce. 

Because  of  their  efficiency  as  feeders  on  insect  pests,  a  number  of  kinds 
have  been  introduced  into  this  country  to  attack  the  special  insects  of 
their  native  lands  which  have  reached  the  United  States  and  have  become 
pests  here.  Among  these  are  the  Vedalia  (Novius  cardinalis  Muls.) 
(See  Fig.  216),  imported  from  Australia  to  attack  the  Cottony-cushion  or 
Fluted  Scale;  the  Mealy-bug  Destroyer  (Cryptolcemus  montrouzieri  Muls.), 
brought  also  from  Australia  to  attack  several  kinds  of  Mealy-bugs  found 
in  California;  the  Steel-blue  Lady  beetle  (Orcus  chalybeus  Boisd.)  which 
feeds  on  a  number  of  kinds  of  Armored  Scales  ;  and  the  Black  Lady  beetle 
(Rhizobius  ventralis  Erichs.)  which  is  an  active  enemy  of  the  Black  Scale 
(Saissetia  olece  Bern.)  ;  besides  numerous  other  species.  Many  of  these 
imported  forms  have  done  valiant  work  in  their  attacks  upon  their 
ancient  foes  in  the  country  to  which  both  have  come,  but  in  some  cases 
this  attempt  to  aid  nature  in  the  control  of  insect  pests  has  been  less 
successful,  and  it  is  evident  that  the  success  of  each  experiment  of  this 
kind  can  rarely  be  determined  beforehand.  (See  Cottony  Cushion  Scale, 
Chapter  XXVI). 

Family  Tenebrionidae  (Darkling  Beetles).  —  This  rather  large  family  of  beetles 
contains  many  forms  found  on  the  ground  and  superficially  resembling  the  Cara- 
bidse.     They  are  usually  rather  slow  of  movement,  however,  feed  on  vegetable 
instead  of  animal  food,   and  while  their  fore  and  middle   _____  _  , 

tarsi  are  each  composed  of  five  segments  as  in  the  Carabids, 
their  hind  tarsi  each  have  only  four.  They  are  particularly 
abundant  in  the  Southwest  and  West,  though  a  number 
are  present  practically  everywhere. 

The  Yellow  Meal-Worm  (Tenebrio  molitor  L.)  about 
three-quarters  of  an  inch  long  (Fig.  127),  is  often  found 
around  stores  of  grain,  in  pantries,  stables  etc.,  and  its  larva 
which  closely  resembles  a  wireworm,  feeds  upon  meal  and 
similar  materials.  It  is  often  raised  as  food  for  cage  birds. 
Where  abundant,  a  thorough  cleaning  out  of  infested  places, 


followed  by  sprinkling  air-slaked  lime  around,  or  fumigation    molitor  L.),   about 

of  the  infested  material  with  Carbon  disulfid,  is  all  that  is    natural  size.    (Orig- 

inal.) 
necessary. 

Family  Meloidae  (Blister  Beetles).  —  The  insects  of  this  family  also 
have  but  four  segments  to  each  hind  tarsus.  The  body  is  quite  cylin- 
drical and  rather  soft,  and  the  head  joins  the  thorax  by  a  distinct  neck 
(Fig.  128).  Many  of  the  members  of  this  family  contain  a  substance 


136 


APPLIED  ENTOMOLOGY 


called  cantharidin,  which  when  applied  to  the  skin,  produces  blisters. 
The  bodies  of  these  species,  powdered,  are  used  in  medicine  under  the 
name  "  cantharides "  or  "  Spanish  flies,"  for  blistering  purposes. 

A  dozen  or  twenty  kinds  of  Blister  beetles,  averaging  from  half 
an  inch  to  over  an  inch  in  length  are  more  or  less  serious  pests  as  adults, 
feeding  during  the  summer  or  fall  on  foliage  and  blossoms,  various  vege- 


FIG.  128. — Adult  Blister  Beetles:  a,  Black  Blister  Beetle  (Epicauta  pennsylvanica 
De  G.) ;  6,  Ash-gray  Blister  Beetle  (Macrobasis  unicolor  Kby.) ;  c,  Striped  Blister  Beetle 
(Epicauta  vittala  Fab.);  all  about  natural  size.  (Modified  from  U.  S.  D.  A.  Bulletins.) 

tables  and  ornamental  plants  being  attacked.  Vegetable  crops  are 
sometimes  seriously  affected.  The  larvse  on  the  other  hand,  feed  on  the 
eggs  of  various  species  of  grasshoppers  and  are  therefore  beneficial. 
The  adults  are  not  easily  controlled  as  they  are  rather  resistant  to  arseni- 
cal poisons,  and  as  they  fly  freely,  it  is  difficult  to  reach  them  with  contact 
insecticides.  In  cases  where  stomach  poisons  can  be  applied,  arsenate 

of  lead,  taking  about  4  Ib.  (if  the 
paste  be  used)  to  50  gal.  of  water, 
has  proved  the  best  treatment. 
Where  this  cannot  be  done,  hand- 
picking,  and  screening  valuable 


plants     with 
resorted  to. 


netting,     may     be 


FIG.  129.— Examples  of  adult  Snout 
Beetles  showing  differences  in  the  develop- 
ment of  the  snout.  About  twice  natural 
size.  (Original.) 


RHYNCHOPHORA  (Snout  Beetles) 

The  snout  beetles  are  included 
in  several  families.  Some  are 
called  curculios,  weevils,  and  bill- 
bugs,  and  those  of  one  family,  the 
larvse  of  which  work  in  the  bark 
and  wood  of  trees,  are  called  Engraver  beetles  and  also  bark  borers. 
Over  twenty-five  thousand  species  of  Rhynchophora  are  known  (Fig.  129). 
Except  for  this  last  named  family,  most  snout  beetles  feed  on  fruits, 
nuts,  etc.,  though  a  few  attack  stems  and  leaves.  The  white,  ntl^ly 
always  footless  larvse,  also  feed  for  the  most  part  on  such  materials, 'and 
a  number  are  very  destructive  and  therefore  important  pests. 


THE  COLEOPTERA 


137 


The  Plum  Curculio  (Conotrachelus  nenuphar  Herbst). — This  insect 
is  a  native  of  the  United  States  and  formerly  fed  upon  the  wild  plum  and 
thorn  fruits,  but  now  also  attacks  cultivated  plums,  prunes,  cherries, 
nectarines,  apricots,  apples  and  peaches.     It  is  found  practically  every- 
where east  of  the  Rocky  Mountains,  though  in 
the  western  portion  of  this  area  it  seems  to  be  of 
less  importance  than  elsewhere.     The  adult  beetle 
(Figs.  130  and  131)  is  small,  being  only  about  a 


FIG.  130.  FIG.  131. 

FIG.  130. — Adult  Plum  Curculio  (Conotrachelus  nenuphar  Hbst.),  view  from  above. 
About  five  times  natural  size.  (Modified  from  U.  S.  D.  A.  Bur.  Ent.  Bull.  103.) 

FIG.  131. — Side  view  of  adult  Plum  Curculio  showing  humps  on  the  back.  Enlarged 
about  five  times.  (Modified  from  U.  S.  D.  A.  Bur.  Ent.  Bull.  103.) 

fifth  of  an  inch  long,  dark  colored  as  a  whole  but  mottled  with  gray 
and  brown.  Its  elytra  are  rough  and  on  each  is  a  black,  shining  hump 
a  little  behind  the  middle. 

This  pest  spends  the  winter,  or  the  colder  months  in  the  South,  hiding 
in  any  protected  place  it  can  find,  particularly  in  the  woods,  in  stone 
walls  or  under  leaves.  It  appears 
about  the  time  the  plum  buds  open  in 
spring  and  feeds  more  or  less  on  the 
developing  leaves.  When  the  fruit 
begins  to  develop,  the  beetles  turn 
their  attention  to  it,  feeding  by  cutting 
a  circular  hole  through  the  skin  and 
consuming  the  .flesh  beneath  to  a 
depth  about  equal  to  the  length  of 
the  snout  of  the  insect.  They  also 
begin  now  to  lay  their  eggs  in  the 
young  plums,  cutting  a  hole  in  the 
skin  and  then  running  the  snout  ob- 
liquely into  the  flesh  beneath.  In 
this  cavity  the  egg  is  placed  and  it  is 
then  pushed  farther  in  by  the  snout. 
The  beetle  next  cuts  a  crescent-shaped 
slit  through  the  skin  close  to  the 
egg  (Fig.  132)  and  carries  this  down  through  the  flesh  beneath  the  egg 
which  thus  comes  to  lie  in  a  sort  of  flap  which  wilts  and  remains  soft,  and 
the  crushing  of  the  egg  by  the  growth  of  firm  tissue  there  is  prevented. 


FIG.  132. — Egg  puncture  and  feeding 
puncture   of    Plum    Curculio    in   young 
(From  U.  S.  D.  A.  Farm.  Bull. 


138 


APPLIED  ENTOMOLOGY 


Several  hundred  eggs  are  laid  in  this  way  and  the  "spot  and  crescent" 
marks  of  the  insect  on  small  plums  are  familiar  to  plum  growers.  The 
fruit  often  pours  out  gum  at  these  places,  probably  in  an  attempt  to 
repair  the  injury. 

The  eggs  hatch  in  a  week  or  less  and  the  tiny  whitish  grub  bores 
through  the  flesh,  and  in  stone  fruits  passes  to  the  stone,  around  which  it 
feeds  for  about  two  weeks  or  until  full-grown.  It  then  leaves  the  fruit, 
and  as  this  in  most  cases  has  fallen  before  this  time  because  of  the  injury, 
the  larva  finds  itself  on  escaping,  on  the  ground.  Into  this  it  now  burrows 
an  inch  or  two  and  pupates.  About  a  month  later  the  adult  beetle 
emerges,  comes  to  the  surface  of  the  ground  and  attacks  fruit  for  food,  egg- 
laying  rarely  if  ever  taking  place  at  this  season,  and  when  cold  weather 
comes  on  it  locates  in  some  protected  place  for  the  winter.  There  is 
accordingly,  but  one  generation  a  season. 


FIG.   133. — Apple  showing  injury  by  Plum  Curculio  in  fall.      (Modified  from  III.  Agr.  Exp. 

Sta.  Bull.  98.) 


This  insect,  both  by  its  feeding  and  egg-laying  punctures,  affects 
the  value  of  the  fruit  not  entirely  destroyed,  not  only  in  appearance  but 
by  the  opportunity  these  cuts  afford  for  the  entrance  of  the  spores  of 
disease-producing  fungi,  and  the  destruction  in  the  United  States  which 
it  causes  has  been  estimated  at  over  eight  million  dollars  annually. 
While  the  insect  rarely  succeeds  in  developing  in  the  apple,  the  punctures 
cause  dropping  of  the  fruit  .or  its  malformation,  and  the  production  of 
hard,  woody  places  in  the  pulp.  In  the  fall  its  feeding  holes  in  apples 
also  cause  much  injury  (Fig.  133). 

Control. — No  one  method  nor  even  all  the  methods  of  control  taken 
together  will  give  entire  freedom  from  this  pest.  A  combination  of 


THE  COLEOPTERA  139 

treatments,   however,   will  accomplish  considerable  in  this  line.     The 
usual  measures  taken  are  as  follows: 

(1)  Remove  all  opportunities  for  the  successful  wintering  of  the 
adults,  as  far  as  possible.  Rubbish,  stone  walls,  and  trash  of  all  sorts 
should  be  removed.  Plum  orchards  near  woodland  are  poorly  located 
from  this  standpoint.  (2)  The  curculio  prefers  shade  in  which  to  work, 
and  larvae  even  inside  fallen  fruit  are  unable  to  survive  any  long  exposure 
to  direct  sunlight.  The  trees  therefore  should  be  so  pruned  as  to  let  the 
sunlight  through  all  parts,  and  fallen  fruit  should  be  exposed  to  the,  sun 
by  proper  treatment  of  the  ground  under  the  tree.  (3)  Fowls  and  hogs 
will  eat  many  of  the  larvae  in  the  fallen  fruit  and  larvae  or  pupae  in  the 
ground,  and  should  be  allowed  to  run  under  the  trees;  or  thorough,  shallow 
cultivation  under  the  trees  should  be  given  from  the  time  the  larvae  begin  to 
leave  the  fruit  until  at  least  6  weeks  later,  to  destroy  the  insects  there. 

(4)  Spraying  with  arsenate  of  lead  either  alone  or  combined  with  the 
self-boiled  lime-sulfur  has  been  fairly  successful  if  the  applications  be 
thorough  and  at  the  right  times.     For  plums  spraying  with  2j/£  Ib.  of 
lead  arsenate  paste  (1J4  Ib.  of  the  powder)  in  50  gal.  of  water  or  lime- 
sulfur  as  soon  after  the  blossoms  fall  as  leaves  begin  to  develop,  and  the 
treatment  repeated  8  or  10  days  later  has  proved  the  best  method. 
Cherries  can  be  treated  in  the  same  way.     With  peaches,  2  Ib.  of  the 
arsenate  in  50  gal.  of  water,  to  which  the  milk  of  lime  obtained  by  slaking 
2  Ib.  of  quick  lime  has  been  added,  is  sprayed  as  soon  as  the  "shucks" 
are  beginning  to  shed  from  the  blossoms.     About  3  weeks  later  a  spray 
of  2  Ib.  of  the  arsenate  in  50  gal.  of  the  self-boiled  lime-sulfur  is  made.     A 
third  treatment  about  a  month  before  the  fruit  begins  to  ripen,  using  the 
lime-sulfur  only,  is  also  often  given.     For  apples  the  precautions  neces- 
sary in  spraying  stone  fruits  with  arsenate  of  lead  need  not  be  taken. 
Here  the  treatments  commonly  given  for  the  Codling  Moth  (see  Chapter 
XXIX)  are  also  effective  at  those  times  for  the  Curculio,  though  later 
similar  applications  may  also  be  necessary  if  the  insects  are  abundant. 

(5)  Where  only  a  few  stone-fruit  trees  are  involved,  jarring  them  early 
in  the  morning,  after  spreading  white  cloth  under  them,  is  a  good  treat- 
ment.    The  beetles  at  that  time  of  day  are  sluggish  and  drop  onto  the 
cloth  when  the  tree  is  given  a  sudden  blow,  and  they  can  then  be  gathered 
and  destroyed.     This  should  be  begun  as  soon  as  the  blossoms  have  all 
fallen  and  continued  until  the  beetles  no  longer  appear. 

The  Plum  Gouger  (Coccotorus  scutellaris  Lee.). — This  plum  pest  like  the  last, 
is  a  native  of  this  country  and  is  found  from  New  York  west  to  the  Rocky  Moun- 
tains and  south  to  Texas.  It  appears  to  be  destructive,  however,  mainly  west  of 
the  Mississippi  River.  The  adult  (Fig.  134)  is  somewhat  larger  than  the  Plum 
Curculio.  The  head  and  thorax  are  dull  yellow  and  the  elytra  are  lead-gray  in 
color,  and  the  surface  is  without  any  humps  or  other  irregularities.  In  many 
regards  the  habits  of  the  Gouger  are  like  those  of  the  Plum  Curculio,  but  it  leaves 


140  APPLIED  ENTOMOLOGY 

its  winter  quarters  earlier  than  the  last  named  insect  and  feeds  for  a  time  on  the 
opening  buds  and  leaves,  gouging  holes  in  the  blossoms  (Fig.  1346)  and  thus  caus- 
ing them  to  drop  off.  Feeding  holes  and  egg  punctures  in  the  young  plums 
(Fig.  134c)  are  holes  into  the  flesh  in  some  of  which  the  eggs  are  placed,  but  many 
more  holes  are  made  than  eggs  deposited.  The  grubs  work  their  way  to  and  into 
the  stone  or  pit  and  feed  on  the  flesh  (seed)  within  until  full  grown.  Each  then 
gnaws  a  hole  through  the  stone,  after  which  it  pupates  inside  the  stone,  the  adult 
appearing  in  late  August  and  September.  There  appears  to  be  but  one  insect  in 
a  fruit. 


a  b  c 

FIG.  134. — Plum  Gouger  (Coccotorus  scutellaris  Lee.) :  a,  adult  beetle  about  three 
times  natural  size;  6,  plum  blossoms  attacked  at  their  bases  by  the  beetle;  c,  young  plums 
punctured  by  the  beetle.  (Modified  from  Minn.  Agr.  Exp.  Sta.  Bull.  66.) 

Plums  attacked  by  the  Plum  Gouger  do  not  drop,  but  mature  on  the  tree,  but 
such  plums  are  worthless  for  market  because  of  the  injured  spots  and  because  of 
the  deformed  fruit  produced. 

Control. — Picking  off  the  injured  plums  before  the  beetles  emerge  in  the  fall 
has  been  recommended  as  a  method  of  control  for  this  insect,  and  jarring  in  spring 
has  also  been  advised,  though  the  beetles  do  not  drop  as  freely  as  in  the  case  of  the 
Plum  Curculio.  It  is  possible  that  spraying  with  arsenate  of  lead  as  for  the 
Curculio,  making  the  first  application  as  soon  as  the  buds  are  open  enough  to 
provide  any  surface  for  the  poison  to  adhere  to,  may  prove  of  some  value. 

The  Cotton  Boll  Weevil  (Anthonomus  grandis  Boh.). — This  is  at  the 
present  time  the  most  serious  insect  pest  of  cotton  which  we  have. 
Recent  estimates  place  the  destruction  by  the  boll  weevil  at  about  400,000 
bales  per  year,  which  at  average  prices  for  the  cotton  not  thus  destroyed 
would  be  many  millions  of  dollars.  Diversification  of  crops  has  come 
into  practice,  however,  where  the  cotton  crop  has  suffered,  so  that  in  a 
number  of  the  affected  States  the  total  value  of  all  crops  after  the  appear- 
ance of  the  weevil,  has  been  greater  than  before.  In  some  cases  then, 
the  loss  to  cotton  has  been  more  than  made  up  by  turning  to  other  crops, 
but  the  reduction  in  the  amount  of  cotton  needed  for  use  in  the  world  is 
important. 

The  cotton  boll  weevil  is  a  native  of  tropical  America,  whence  it 
spread  northward  through  Mexico,  and  about  1892  entered  Texas.  Since 
that  time  it  has  extended  its  area  of  infestation,  reaching  the  Atlantic 


THE  COLEOPTERA  141 

Coast  in  Georgia  in  1916  and  in  time  it  will  probably  be  present  every  where 
in  the  cotton  belt,  except  perhaps  in  the  more  arid  portions  and  in  places 
where  it  can  find  little  protection  during  cold  weather. 

The  adult  boll  weevil  (Fig.  135)  varies  considerably  in  size  but  aver- 
ages about  a  quarter  of  an  inch  in  length.  When  it  first  emerges  from 
the  pupa  it  is  light  brown,  but  it  soon  becomes  gray  or  almost  black. 
It  winters  as  the  adult,  hiding  under  rubbish,  in  cracks  in  the  ground,  in 
Spanish  moss  growing  on  the  trees,  or  in  fact  in  any  protected  place, 
though  those  which  winter  in  the  cotton  fields  appear  to  be  least  protected 
and  hence  least  liable  to  survive,  while  those  in  wooded  areas  winter  more 
successfully. 


a  be 

FIG.  135. — Cotton  Boll  Weevil  (Anthonomus  grandis  Boh.) ;  a,  side  view  of  adult 
beetle  enlarged  about  six  times;  b,  larva  (grub);  c,  pupa;  both  much  enlarged.  (From 
Sanderson:  Insects  Injurious  to  Farm,  Garden  and  Orchard.) 

In  spring  the  beetles  leave  their  winter  quarters,  the  time  generally 
varying  from  March  to  the  last  of  June.  "In  the  spring  and  throughout 
the  fruiting  season  of  cotton  the  eggs  are  deposited  by  the  female  weevils 
in  cavities  formed  by  eating  into  the  fruit  of  the  plant.  An  egg  hatches 
under  normal  conditions  in  about  three  days,  and  the  grub  immediately 
begins  to  feed.  In  from  7  to  12  days  the  larva  or  grub  passes  into  its 
pupa  stage,  corresponding  to  the  cocoon  of  butterflies  and  moths.  This 
stage  lasts  from  3  to  5  days.  Then  the  adult  issues,  and  in  about  5  days 
begins  the  production  of  another  generation.  Climatic  conditions  cause 
considerable  variation  in  the  duration  of  the  stages,  but  on  an  average 
it  requires  from  2  to  3  weeks  for  the  weevil  to  develop  from  the  egg  to 
the  adult.  Males  and  females  are  produced  in  about  equal  numbers. 
The  males  feed  upon  the  squares  and  bolls  without  moving  until  the  food 
begins  to  deteriorate.  The  females  refrain  from  depositing  in  squares 
visited  by  other  females.  This  applies  throughout  most  of  the  season, 
but  late  in  the  fall,  when  all  the  fruit  has  become  infested,  several  eggs 
may  be  placed  in  a  single  square  or  boll.  As  many  as  15  larvae  have  been 
found  in  a  boll.  The  squares  are  greatly  preferred  as  food  and  as  places 


142  APPLIED  ENTOMOLOGY 

for  depositing  eggs.  As  long  as  a  large  supply  of  squares  is  present,  the 
bolls  are  not  damaged  to  any  serious  extent.  The  bolls,  therefore,  have 
a  fair  chance  to  develop  as  long  as  squares  are  being  formed."  (Marlatt, 
Farmers'  Bulletin  848,  U.  S.  D.  A.,  1917). 

These  insects  are  extremely  prolific.  It  has  been  calculated  that  from 
a  single  pair  of  the  beetles  in  spring  there  might  be  12,755,100  progeny  by 
the  end  of  the  season,  but  many  factors  prevent  this  from  actually  being 
the  case.  Infested  squares  soon  drop  off  the  plant  and  on  the  ground 
generally  become  so  heated  as  to  kill  the  Iarva3  in  them.  Parasites  and 
other  enemies,  particularly  ants,  attack  the  insect,  and  other  minor 
factors  are  of  some  value.  All  of  these  combined,  however,  only  prevent 
a  bad  condition  from  becoming  worse,  and  control  measures  must  be 
resorted  to. 

Control. — There  are  several  control  measures  which  seem  to  give  par- 
tially satisfactory  results.  One  of  these  is  to  destroy  all  infested  plants  in 
the  fall,  particularly  in  the  southern  part  of  the  area  where  the  weevil  is 
found.  This  kills  great  numbers  of  adults  about  ready  to  hibernate,  many 
more  still  in  early  stages  in  the  plants,  leaves  no  food  for  those  escaping, 
and  prevents  the  production  of  the  latest  beetles,  thus  reducing  the  num- 
ber to  hibernate.  It  also  permits  fall  or  winter  plowing  which  is  good 
farm  practice  in  cotton  growing.  Generally  this  destruction  of  the  plants 
should  occur  in  October,  even  though  a  little  cotton  is  lost  in  this  way. 
The  destruction  of  any  hibernating  weevils  wherever  possible  is  advan- 
tageous. Crop  rotation  is  also  desirable,  as  many  of  the  weevils  winter 
near  the  cotton  fields  and  do  not  fly  far  in  the  spring.  Any  methods 
which  will  hasten  crop  production,  such  as  fertilizers,  the  use  of 
early  maturing  varieties  and  early  planting,  are  desirable.  Dusting 
the  young  plants  with  arsenate  of  lead  or  arsenate  of  lime  blown 
directly  onto  them  has  frequently  given  good  results.  The  use  of  all 
these  methods  together  gives  considerable  relief  from  the  attacks  of  this 
pest,  and  the  problem  how  far  to  go  in  carrying  them  out  is  largely  one  of 
their  cost  as  compared  with  the  value  of  the  cotton  which  will  be  saved  by 
the  treatments.  Hand  picking  of  the  weevils  and  of  infested  squares  has 
not  generally  proved  successful.  •  As  the  insect  has  thus  far  been  known  to 
feed  only  on  cotton  and  the  wild  cotton  of  Arizona  (where  it  probably 
does  not  yet  occur),  the  danger  of  its  increasing  on  other  food  plants  does 
not  at  present  seem  to  exist. 

The  White  Pine  Weevil  (Pissodes  strobi  Peck). — This  native  enemy  of  the 
pine  occurs  practically  wherever  the  white  pine  is  found,  viz.,  from  New  Bruns- 
wick and  Canada  west  to  Minnesota,  and  south  to  North  Carolina.  It  also 
attacks  our  other  native  pines  and  the  spruces  somewhat. 

The  adults  (Fig.  136)  pass  the  winter  in  protected  places,  possibly  in  the 
ground,  and  in  spring  gather  on  the  terminal  shoots  (leaders)  of  the  pines,  generally 
on  the  trunk  leader  in  preference  to  those  of  the  branches.  Here,  near  the  tip, 


THE  COLEOPTERA 


143 


they  feed  on  the  bark  and  soon  cut  tiny  holes  in  it,  placing  their  eggs  in  the  holes. 
The  borers  which  hatch  from  these  eggs  tunnel  downward  through  the  leader 
(Fig.  137)  and  by  August  have  finished  feeding  and  pupate  in  the  tunnels.  After 
transformation  to  the  beetle  has  been  completed,  these  escape  to  the  outside  by 
making  round  holes  through  the  stems  they  are  in.  Later  they  hibernate  for  the 
winter. 

The  adult  beetle  is  about  a  quarter  of  an  inch  long,  reddish-brown  or  some- 
what darker,  with  a  white  spot  on  each  elytron  not  far  from  its  outer  end,  which 
when  the  elytra  are  at  rest  brings  these  spots 
not  far  from  the  end  of  the  body.  There 
are  also  several  irregular  areas  on  the  elytra 
somewhat  lighter  than  the  ground  color. 

Control— Spraying  the  leaders  before  the 
beetles  gather  on  them  in  the  spring,  with 
arsenate  of  lead,  using  one  pound  more  than 
the  standard  formula  for  the  paste,  is-  one 
method  of  control.  Collecting  the  beetles 
after  they  have  begun  to  gather  on  the 
leaders  is  also  practiced,  jarring  them  off  into 


FIG.  136.  FIG.  137. 

FIG.  136. — Adult  White  Pine  Weevil  (Pissodes  strobi  Peck),  enlarged  nearly  three 
times.  (After  Felt:  N.  Y.  State  Mus.  Mem.  8.) 

FIG.  137.— Work  of  White  Pine  Weevil  in  terminal  twigs  of  pine.  (After  Felt:  N.  Y. 
State  Mus.  Mem.  8.) 

a  net  held  beneath,  as  they  generally  drop  instead  of  flying  when  disturbed 
then.  This  treatment  should  be  repeated  several  times  at  4  or  5-day  intervals. 
It  can  hardly  be  done  except  on  small  trees. 

The  injury  caused  by  these  insects  aside  from  their  feeding,  is  the  killing  of  the 
leader  which  stunts  the  growth  of  the  tree.  Usually  a  side  branch  grows  up  to 
replace  the  lost  leader  and  makes  the  tree  deformed,  or  when  two  do  this,  a  fork 
is  produced.  In  either  case  the  value  of  the  tree  either  for  timber  or  as  an  orna- 
ment is  largely  lost.  The  work  of  the  weevil  is  most  serious  and  also  most 
frequent  on  young  trees,  making  its  injuries  more  serious  on  this  account. 

The  Alfalfa  Weevil  (Phytonomus  posticus  Gyll.). — This  European  insect  was 
discovered  in  this  country  about  1904  and  is  now  found  in  parts  of  Utah,  Idaho 
and  Wyoming,  and  is  gradually  spreading.  The  adult  (Fig.  138)  is  a  snout 
beetle  only  about  three-sixteenths  of  an  inch  long,  brown  when  fresh  but  almost 


144  APPLIED  ENTOMOLOGY 

black  after  a  time.  It  winters  as  the  adult  close  to  the  ground  or  in  crevices 
there,  and  in  some  cases  under  rubbish,  and  in  severe  winters  many  are  killed  by 
the  cold.  As  soon  as  warm  days  come  the  weevils  become  active  and  lay  eggs 
in  the  dry  alfalfa  stems,  before  the  regular  laying  season,  and  the  larvae  from  these 
eggs  attack  the  young  plants,  often  causing  serious  injury.  The  weevils  also  feed 
on  the  plants  quite  freely  at  this  season.  After  a  few  weeks  the  true  egg-laying 
period  begins  and  the  adults  now  puncture  the  living  alfalfa  stems  and  lay  their 
eggs  in  them,  this  process  usually  being  finished  by  the  tenth  of  June,  though  a 
few  eggs  are  laid  much  later.  The  eggs  hatch  in  about  ten  days  and  the  larvae 
(Fig.  139)  consume  the  alfalfa  leaves,  those  from  the  ones  laid  early  beginning  to 


FIG.  138.  FIG.  139.  FIG.  140. 

FIG.  138. — Adult  Alfalfa  Weevil  (Phytonomus  posticus  Gyll.)  much  enlarged.  (From 
U.  S.  D.  A.  Bur.  Ent.  Bull.  112.) 

FIG.  139. — Side  view  of  larva  of  Alfalfa  Weevil,  greatly  enlarged.  (From  U.  S.  D.  A. 
Bur.  Ent.  Bull.  112. 

FIG.  140. — Cocoon  of  the  Alfalfa  Weevil,  greatly  enlarged.  (From  U.  S.  D.  A. 
Bur.  Ent.  Bull.  112.) 

feed  in  May,  while  later  individuals  are  feeding  until  into  July  or  even  August, 
with  some  stragglers  later.  The  larval  period  varies  greatly,  but  an  average 
length  of  time  in  this  stage  would  be  perhaps  a  month.  When  full-grown  the 
larva  goes  to  some  protected  place  such  as  a  dry,  curled  leaf  or  dead  vegetation 
near  the  ground  and  spins  a  cocoon  (Fig.  140)  in  the  form  of  a  loose  network,  in 
which  it  pupates.  This  stage  lasts  about  10  days  before  the  appearance  of  the 
beetle.  In  late  summer  these  beetles  begin  to  look  for  winter  shelter  and  in  this 
search  may  spread  some  distance.  In  spring  a  somewhat  similar  flight  in  search 
of  food,  also  increases  their  spread.  This  insect  feeds  on  various  species  of  clover 
in  addition  to  alfalfa,  and  as  it  seems  to  be  persistently  spreading,  it  must  be 
considered  a  menace  to  nearly  all  parts  of  the  country. 

Control. — The  most  serious  injury  to  the  crop  is  that  caused  by  the  spring 
feeding  before  the  first  cutting,  and  this  also  delays  the  production  of  the  second 
crop.  Any  treatment  of  the  field,  such  as  disking  it  with  a  harrow,  which  will 
hasten  growth  at  that  time  will  be  a  gain.  Spraying  these  fields  with  arsenate  of 
lead,  1  Ib.  of  the  paste  in  50  gal.  of  water,  appears  to  reach  many  of  the  insects 
and  be  quite  effective.  Pasturing  during  the  spring  months,  dividing  the  fields 
so  that  each  piece  may  be  grazed  close  about  once  every  2  weeks,  and  continuing 
this  until  most  of  the  eggs  of  the  weevil  have  been  laid,  has  also  given  good 
results,  as  has  cutting  and  feeding  the  crop  before  the  eggs  hatch.  Spraying 


THE  COLEOPTERA 


145 


the  stubble  after  the  first  cutting,  or  treating  such  fields  by  going  over  them  once 
or  twice  with  a  disk  or  spring-tooth  harrow,  followed  by  dragging  with  a  brush 
drag,  to  give  a  dust  mulch,  will  protect  the  second  crop  but  is  probably  less  valu- 
able than  the  earlier  spring  methods. 

The  Potato  Stalk  Weevil  (Trichobaris  trinotata  Say). — This  pest  of  the  potato 
is  widely  distributed  over  the  United  States  east  of  the  Rocky  Mountains  except 
in  the  more  northerly  States.  It  has  also  been  reported  from  California.  The 
beetle  is  gray  with  a  black  head  and  three  black  spots  at  the  base  of  the  elytra  and 
is  about  a  fifth  of  an  inch  long.  It  winters  in  the  old  potato  stalks  and  when  the 
young  potato  plants  are  large  enough  it  makes  small  holes  in  the  stalks  and 
sometimes  in  the  branches,  in  which  the  eggs  are  deposited.  The  eggs  hatch  in 
a  week  or  10  days  and  the  grubs  burrow  downward  toward  the  roots  and  after 
reaching  them  turn  upward  again,  enlarging  the  burrows.  This  tunnelling 
weakens  the  stalks  and  causes  the  plant  to  wilt  and  die.  Pupation  takes  place  in 
the  stalks,  usually  near  the  ground,  and  the  adults  are  produced  in  from  1  to  2 
weeks,  but  generally  do  not  leave  the  stalks  until  the 
following  spring.  A  number  of  individuals  may  be  present 
in  a  single  stalk.  Other  food  plants  are  Jamestown  weed, 
horse  nettle,  eggplant  and  other  plants  of  the  family 
Solanacese. 

Control. — Where  the  plants  have  wilted  and  dying  leaves, 
and  an  examination  of  the  stem  shows  borers  to  be  present, 
pulling  up  and  burning  infested  stalks  is  desirable.  Prac- 
tically the  same  result  may  be  obtained  by  collecting  and 
burning  all  the  stalks  as  soon  as  the  crop  has  been  dug,  thus 
destroying  the  weevils  in  them.  The  destruction  of  all 
weeds  around,  which  are  liable  to  be  infested  by  the  insects, 
this  work  being  done  after  the  egg-laying  season  is  over,  is 
also  desirable. 

The  Sweet  Potato  Weevil  (Cylas  formicarius  Fab.).— 
This  is  a  tropical  insect  which  was  first  reported  in  the 
United  States  about  1875.     It  now  occurs  in  the   most 
southerly  States  from  Georgia  to  Texas,    attacking   the 
sweet  potato.     The  adult  (Fig.  141)  unlike  the  other  snout 
beetles  here  considered,  is  very  slender,  about  a  quarter  of  an  inch  long,  with 
a  black  head,  reddish  prothorax  and  legs,  and  dark  blue  elytra.     The  prothorax 
is  strongly  narrowed,  forming  a  noticeable  "waist"  for  the  insect. 

The  eggs  of  this  pest  are  laid  singly  in  small  holes  eaten  in  the  stem  or  any 
exposed  potato.  They  hatch  in  a  few  days  and  the  grubs  in  the  stems  burrow 
through  them  down  to  the  potato,  then  tunnel  irregularly  about,  becoming  full- 
grown  in  2  or  3  weeks.  The  grub  now  forms  a  cavity  and  in  this  it  pupates  for 
about  a  week  and  then  a  few  days  later  eats  its  way  out  and  may  leave  the  potato, 
or  may  remain  there  and  lay  eggs  for  another  generation  in  the  same  potato 
in  which  it  itself  developed,  and  this  process  may  continue  until  the  entire 
potato  is  destroyed.  As  long  as  food  is  available,  one  generation  after  another  is 
thus  produced,  but  when  no  more  can  be  found  the  adult  insects  live  along  for  a 
considerable  time  without  feeding,  attacking  the  plants  and  laying  their  eggs  in 
them  whenever  more  appear.  Adult  beetles  feed  on  the  leaves  and  stems  somewhat. 
10 


FIG.  141.— Adult 
Sweet  Potato  Weevil 
(Cylas  formicarius 
Fab.)  enlarged  over 
five  times.  (From 
U.  S.  D.  A.  Farm. 
Bull.  856.) 


146 


APPLIED  ENTOMOLOGY 


As  soon  as  tunnels  in  the  potato  are  formed,  the  tissues  around  them  change 
color  and  decay  soon  follows,  so  that  an  attack  quickly  ruins  the  value  of  the 
crop. 

Control. — Sweet  potatoes  found  infested  ever  so  slightly  should  immediately 
be  destroyed,  either  by  feeding  to  stock  or  in  some  other  way.  If  any  area 
becomes  infested  no  sweet  potatoes  should  be  planted  there  for  several  years, 
and  as  it  is  probable  that  the  insect  can  also  breed  in  the  wild  morning  glory,  all 
plants  of  this  species  should  also  be  destroyed  as  far  as  possible  within  the  area. 
Spraying  the  plants  with  arsenate  of  lead  or  other  stomach  poison,  applied  as  soon 
as  the  beetles  appear  has  recently  given  encouraging  results.  Following  sprays 
at  about  ten-day  intervals  may  be  given  if  necessary. 

Family  Ipidse  (formerly  Scolytidse)  (Bark  beetles  or  Engraver  beetles). 
The  members  of  this  family  are  borers  and  nearly  all  attack  the  inner 
bark  or  wood  of  trees.  They  are  small  insects,  from  one  twenty-fifth 

to   two-fifths   of   an    inch   long, 

brownish  or  blackish  in  color, 
and  usually  with  cylindrical 
bodies  (Fig.  142).  In  habits 
they  form  two  chief  groups.  In 
the  so-called  Ambrosia-beetles 
the  tunnels  extend  through  the 
wood  and  the  young  develop 
there:  in  the  True  Bark-beetles 
the  tunnels  are  formed  either  in 
the  inner  bark  or  between  this 
and  the  wood.  The  adult  in 


FIG.  142.  FIG.  143. 

FIG.   142. — Adult  Bark  Beetles,  greatly  enlarged.      (Modified  From  Felt:  tf.    Y.  Stale 
Mus.  Mem.  8.) 

FIG.   143. — Work  of  Bark  Beetles  on  inside  of  bark,  slightly  reduced.      (Original.) 

either  case  cuts  a  tunnel  slightly  larger  than  itself  in  to  the  inner  bark 
or  through  this,  but  the  Ambrosia-beetles  continue  it  on,  into  the 
wood.  The  Bark-beetles  having  arrived  at  the  desired  depth,  turn  and 
excavate  one  or  more  channels  between  the  bark  and  the  wood,  which 
become  the  egg  tunnels.  Along  the  sides  of  these  the  eggs  are  deposited, 
either  singly  in  little  hollows,  several  together  in  larger  excavations,  or 


THE  COLEOPTERA  147 

many  in  grooves  of  the  tunnel.  The  larvae,  on  hatching,  excavate  tun- 
nels for  themselves,  leading  away  from  the  egg  tunnel  (Fig.  143)  and 
becoming  larger  with  the  growth  of  the  larvae.  Pupation  is  at  the  end 
of  the  larval  tunnel  in  a  somewhat  wider  portion  and  after  transforma- 
tion the  adult  bores  its  way  to  the  outside.  In  the  case  of  the  Ambrosia- 
beetles  a  fungus  used  as  food  by  the  insects,  grows  on  the  walls  of  the 
tunnels  and  generally  turns  these  walls  black. 

Destruction  by  these  insects  is  mainly  of  forest  and  shade  trees.  As 
nearly  all  the  bark-beetles  appear  to  prefer  dying  bark  in  which  to  live, 
the  refuse  of  cutting  operations,  commonly  termed  "slash/'  will  provide 
much  of  this,  and  most  of  the  insects  will  work  there.  When  slash  comes 
to  an  end,  however,  by  operations  ceasing  in  that  area,  the  increased 
abundance  of  the  insects  due  to  abundant  slash  often  forces  them  for 
lack  of  other  material,  to  turn  to  the  healthy  trees,  themselves  changing 
thereby  from  "secondary"  to  "primary"  foes.  Slash  should  therefore 
be  destroyed  before  beetles  in  it  can  develop  to  the  adult  condition.  Fire 
in  forests  produces  many  dead  and  weakened  trees  also,  frequently  lead- 
ing to  insect  attacks,  and  epidemics,  either  local  or  quite  widespread, 
may  thus  result.  Many  trees  when  the  beetles  bore  into  them,  pour 
out  their  sap  or  resin,  and  some  of  the  insects  may  easily  be 
drowned  in  this.  If  attacked  by  multitudes,  however,  the  supply  of 
sap  becomes  so  reduced  that  the  insects  coming  later  can  accomplish 
their  purpose. 

Removing  "beetle  trees"  before  the  adults  escape,  and  either  remov- 
ing and  burning  the  bark,  floating  the  logs,  or  sawing  the  same  winter  and 
burning  the  slabs  and  trimmings,  are  some  of  the  measures  used  for  the 
protection  of  our  forests  against  these  insects. 

One  species  of  Ipid,  the  Clover  Root -borer,  tunnels  in  the  main 
roots  of  clover.  Several  other  species  attack  fruit  trees,  usually  those 
not  healthy. 

The  Fruit-tree  Bark -beetle  or  Shot-hole  Borer  (Eccoptogaster  rugu- 
losus  Ratz.). — This  European  fruit-tree  pest  has  now  been  in  the  United 
States  about  50  years  and  is  present  nearly  everywhere  east  of  and  in 
many  localities  west  of  the  Mississippi  River,  and  has  been  reported  from 
California.  It  breeds  in  most  of  the  cultivated  deciduous  fruit  trees 
as  well  as  in  several  kinds  of  wild  ones.  The  beetle  (Fig.  144)  is  about 
a  tenth  of  an  inch  long,  almost  black,  except  the  tips  of  the  elytra  and  the 
legs,  which  are  dull  red. 

In  the  spring  the  beetles  enter  the  trees  and  dig  out  egg  channels  one  or 
two  inches  long,  about  parallel  to  the  grain  of  the  wood,  partly  in  this, 
partly  in  the  inner  bark.  Here,  in  little  niches  or  hollows  along  the  sides, 
the  eggs  are  laid.  These  hatch  in  a  few  days  and  the  grubs  burrow, 
first  directly  away  from  the  egg  channel,  then  turning  in  various  directions, 
extend  these  larval  tunnel  sseveral  inches,  and  pupate  at  their  ends. 


148 


APPLIED  ENTOMOLOGY 


When  the  beetles  have  been  formed  there,  they  bore  out  to  the  surface  of 
the  tree  (Fig.  145)  and  soon  begin  to  tunnel  in  again,  to  lay  eggs  for  a 
second  generation  which  in  the  North  becomes  adult  before  winter, 
thus  giving  two  generations  a  year.  In  the  South  with  its  longer  warm 


a 


FIG.  144. — Fruit-tree  Bark-Beetle  (Eccoptogaster  rugulosus  Ratz.);  a,  Adult  Beetle;  b, 
side  view  of  same;  c,  pupa;  d,  larva.  Hair  lines  show  true  length.  (From  U.  S.  D.  A. 
Farm.  Bull.  763.) 

season,  three  or  perhaps  four  generations  may  be  produced  each  year, 
the  adult  beetle  in  some  cases  at  least,  wintering  in  the  tree,  while  in 
others  this  season  may  be  passed  in  the  egg  stage. 

Healthy  trees  are  not  often  attacked  except  when  the  beetles  become 
so  abundant  that  a  sufficient  supply  of  weak  or  dying  ones  is  not  available. 


FIG.   145. — Exit  holes  of  the  Fruit-tree  Bark-Beetle  in  bark  of  a  young  tree,  about  natural 
size.     (From  U.  S.  D.  A.  Farm.  Bull.  763.) 

In  healthy  trees  the  flow  of  gum  sometimes  prevents  the  development  of 
larvae  but  in  time  this  becomes  less  and  the  insects  then  have  a  weakened 
tree  to  attack.  Trunk,  branches  and  twigs  are  perhaps  equally  liable  to 
be  injured.  The  burrows  extending  in  all  directions,  partly  in  the  outer 


THE  COLEOPTERA  149 

surface  of  the  wood,  partly  in  the  inner  bark,  destroy  the  cambium  or 
growing  layer,  often  entirely  girdling  the  twig,  branch  or  trunk  as  the 
case  may  be,  and  causing  its  death. 

Control. — This  must  largely  be  accomplished  by  measures  to  keep 
the  trees  as  vigorous  and  healthy  as  possible.  Any  injured,  broken 
or  otherwise  affected  limbs  should  be  removed  or  so  treated  if  possible, 
as  to  restore  them,  and  close  watch  of  trees  outside  the  orchard,  liable  to 
infestation,  should  also  be  given.  Infested  trees  which  are  still  pouring 
out  gum  can  sometimes  be  saved  by  cutting  back  strongly  and  then  culti- 
vating and  fertilizing  freely.  In  some  cases  a  thick  coat  of  whitewash 
mixed  with  a  little  table  salt  can  be  applied  as  a  repellent  for  the  beetles. 
This  treatment  sometimes  needs  to  be  applied  three  times — once  in 
spring,  again  in  midsummer,  and  once  again  in  the  fall.  Washes  of  soap 
and  carbolic  acid  have  occasionally  been  used  with  some  success,  and  it  is 
claimed  that  the  larvse  can  be  killed  in  their  burrows  by  using  a  carbo- 
lineum  spray  material.  This  is  made  by  dissolving  3  Ib.  of  naphtha 
soap  in  3  gal.  of  hot  water;  adding  a  gallon  of  carbolineum,  stirring 
thoroughly  and  then  diluting  for  use  at  the  rate  of  1  part  of  this  to  4 
of  water. 

These  methods  should  work  equally  well  for  any  of  the  barkbettles 
where  the  bark  is  no  thicker  than  at  the  places  where  these  insects 
attack  the  fruit  trees. 


CHAPTER  XX 


THE  STREPSIPTERA 

These  tiny  insects  are  seldom  seen  except  by  entomologists,  and 
their  parasitic  habits  aid  in  their  concealment.  For  a  long  time  opinions 
were  divided  as  to  where  they  belonged,  some  regarding  them  as  a 
family  of  aberrant  Coleoptera,  while  others  considered  them  as  forming 
an  order.  Recent  studies  seem  to  confirm  the  latter  view  and  the 
group  is  now  generally  rated  as  a  separate  order,  though  its  closest 
relations  are  probably  with  the  beetles. 

The  Strepsiptera,  from  the  meaning  of  this  name,  may  be  called  the 
Twisted-wing  Parasites,  though  the  words  stylops  and  stylopid  are  fre- 
quently used  in  referring  to  them.  The  males  on  reaching  the  adult 
condition  (Fig.  146),  become  free  and  can  fly.  The  females  on  the  other 


FIG.   146. — Male  Strepsipteron  (Xenos  vesparum  Rossi),  rather  more  than  six  times  natural 

size.     (After  Pierce.} 

hand,  remain  partly  within  the  bodies  of  their  host  insects  and  are  worm- 
like  or  grub-like  (Fig.  147)  in  appearance.  The  males  are  very  small, 
soft-bodied  animals,  ranging  from  about  one  to  perhaps  four  twenty- 
fifths  of  an  inch  in  length.  The  eyes  are  more  or  less  stalked  and  the 
antennae  have  one  or  more  segments  elongated  on  one  side.  The  mouth 
parts  are  greatly  modified  but  appear  to  be  of  the  chewing  type,  though 
the  adult  does  not  feed.  On  the  mesothorax  is  a  pair  of  tiny  clubs,  some- 
times rather  flattened,  which  represent  the  front  pair  of  wings.  The 
metathorax  forms  nearly  half  the  entire  length  of  the  body.  It  bears  a 
pair  of  well  developed  wings  which  are  broad  and  fold  lengthwise  when  at 
rest.  The  abdomen  is  composed  of  ten  segments.  The  females  are 
soft  and  resemble  a  rather  long  sack  bearing  traces  of  segmentation,  and 
at  one  end  a  constriction,  beyond  which  is  a  sort  of  knob,  believed  to  be  a 

150 


THE  STREPSIPTERA 


151 


combination  of  the  head  and  thorax;  a  cephalothorax  in  fact.  This 
portion  of  the  body  is  pushed  out  between  two  of  the  body  segments  of 
the  host  during  the  latter  part  of  the  metamorphosis,  thus  becoming 
external  (Fig.  147)  and  the  body  of  the  host  is  distorted  in  this  way. 
The  members  of  this  order  may  be  characterized  as  follows: 
Tiny  insects  which  from  the  first  larval  instar  to  the  adult,  are  internal 
parasites  in  other  insects.  The  male  adult  has  stalked  eyes,  mouth  parts  of 
the  chewing  type,  but  little  or  not  at  all  developed;  antennce  with  one  or  more 
segments  prolonged  laterally;  pro-  and  mesothorax  small,  the  latter  with  a 
pair  of  small  clubs  corresponding  to  the  fore  wings  of  most  insects;  meta- 
thorax  long,  forming  at  least  half  the  length  of  the  body  and  bearing  a  pair  of 


FIG.  147. — Female  Strepsipteron,  top  and  side  views  and  a  Stylopized  Wasp:  a,  end 
of  the  parasite  projecting  between  the  abdominal  segments  of  the  Wasp.  All  greatly 
enlarged.  (After  LeuckarVs  Wandtafeln.) 

broad  wings  which  fold  longitudinally.  The  female  adult  is  worm-like, 
without  feet,  and  located  within  the  body  of  its  host  except  for  a  cephalothorax 
which  protrudes  between  two  abdominal  plates  of  the  latter.  It  is  enclosed 
by  its  pupa  skin.  Metamorphosis  complete. 

These  insects,  often  called  "stylops,"  are  parasitic  only  in  some 
Orthoptera,  Homoptera,  Hemiptera  and  Hymenoptera,  as  far  as  known, 
and  at  the  present  time  only  Gryllotalpa  in  the  Orthoptera  and  Chryso- 
coris  in  the  Hemiptera  are  known  as  hosts  in  those  groups.  Most  of  the 
parasitism  is  of  leaf-hoppers,  wasps  and  the  solitary  bees,  and  these 
are  so  disabled  by  the  removal  of  their  body  fluids  by  the  parasites  that 
' '  stylopized"  individuals  are  unable  to  reproduce  and  are  greatly  lacking 
in  vitality.  Their  bodies  are  often  distorted  also  and  other  changes  are 
produced. 


152  APPLIED  ENTOMOLOGY 

The  eggs  of  the  stylops  appear  to  hatch  within  the  body  of  the  mother 
and  the  young  escape  by  passing  from  the  body  out  into  the  space  between 
this  and  the  pupa  case  of  the  parent  in  which  it  remains,  and  then  through 
an  opening  in  this  at  the  cephalothorax,  thus  reaching  the  open  air. 
They  are  now  on  the  body  of  the  parental  host  and  this  insect  may  carry 
them  to  its  nest,  where  if  it  is  a  colonial  form,  the  stylops  may  find  young 
to  attack  there.  It  is  generally  probable  though,  that  they  leave  the 
parental  host  at  some  place  (possibly  a  blossom)  where  other  insects  of 
the  host  species  will  be  liable  to  visit.  Transferring  onto  such  individuals 
as  chance  may  permit,  the  stylopids  finally  arrive  where  larvae  of  the 
proper  species  are  available,  and  at  once  attack  them.  Thus  far  they 
have  been  active  little  six-legged  larvae,  but  after  burrowing  into  the 
body  of  their  host  larvae  they  change  greatly,  becoming  worm-like  and 
legless.  The  males  finally  enter  a  pupa  stage,  after  which  the  adults 
escape,  but  the  females  remain  throughout  the  rest  of  their  life  in  the 
bodies  of  their  hosts. 

Where  stylopids  are  abundant  and  attack  injurious  species  of  insects, 
such  as  are  most  at  least  of  the  Homoptera,  the  stylopized  individuals, 
being  unable  to  reproduce,  become  of  lessened  importance  and  their 
parasites  must  be  considered  as  beneficial.  Most  of  the  Hymenoptera 
they  attack,  however,  are  beneficial  and  parasitism  in  such  cases  can 
hardly  be  considered  helpful  to  man.  The  group  is  not  sufficiently 
abundant  though,  to  be  an  important  factor  under  ordinary  conditions, 
as  only  about  a  hundred  species  are  known,  but  these  are  widely  dis- 
tributed over  the  globe. 


CHAPTER  XXI 
THE  THYSANOPTERA 

The  Thysanoptera — sometimes  called  Physapoda — are  very  small 
insects,  peculiar  in  many  ways.  The  common  name  for  members  of 
this  group  is  Thrips,  unchanged  in  spelling  whether  one  or  many  are 
referred  to. 

As  a  whole  these  insects  appear  to  have  some  affinities  with  the  hemip- 
teroid  groups  (Anoplura,  Hemiptera  and  Homoptera)  yet  to  be  consid- 
ered, but  are  generally  looked  upon  as  forming  an  order  by  themselves, 
though  in  some  regards  they  seem  to  have  certain  relations  to  the  Cor- 
rodentia  and  Mallophaga.  It  is  not  improbable  that  they  form  a  group 
originating  not  far  from  the  common  trunk  of  all 
the  above-named  orders. 

Thrips  vary  from  one-fiftieth  to  one-third 
of  an  inch  or  more  in  length.  Their  mouth 
parts  (Fig.  148)  form  in  part  a  short,  stout  cone 
attached  far  back  on  the  underside  of  the  head, 
composed  of  the  labrum,  a  portion  of  the  maxillae, 
and  the  labium.  Within  this  cone  are  three 
bristles  consisting  of  the  lobes  of  the  maxillae  and 
one  mandible,  the  other  not  being  developed. 

The  animals  are  sucking  insects.     Four  wings         FlG   148 gide  view  of 

are  usually  present,  rather  long  and  narrow,  with  the  head  and  prothorax  of 
few  veins,  and  fringed  behind  and  generally  in  JiJ^(^^^* 
front  also,  with  slender  hairs,  longer  than  the  Bur,  Ent.  Bull.  68  Part  2.) 
breadth  of  the  wing  itself.  When  at  rest  the 

wings  lie  flat  on  the  top  of  the  abdomen.  In  some  cases  they  are  greatly 
reduced  in  size  or  may  even  be  wanting  entirely.  The  tarsi  are  com- 
posed either  of  one  or  two  segments,  usually  the  latter:  at  the  tip  is  a 
bladder-like  portion  which  can  be  drawn  into  the  segment  or  pushed 
out.  The  abdomen  consists  of  ten  segments,  the  last  either  conical  or 
tubular  in  form. 

Summarizing  these  facts,  the  adult  Thysanoptera  may  be  described  as: 

Small  insects  with  greatly  modified  mouth  parts  forming  a  cone  attached 
to  the  back  part  of  the  head  beneath  and  used  for  sucking.  Wings  four, 
generally  present,  long,  narrow,  with  few  veins,  and  fringed  behind  (usually 
in  front  also)  with  long  hairs.  Tarsi  of  one  or  two  segments,  the  tip  with  a 
bladder-like  swelling  capable  of  being  drawn  into  the  tarsus.  Abdomen  of 
ten  segments,  the  last  either  conical  or  tubular.  Metamorphosis  incomplete 
but  approaching  completeness. 

153 


154  APPLIED  ENTOMOLOGY 

Thrips  feed  on  plant  juices,  puncturing  the  tissues  and  extracting 
the  sap,  leaving  white  marks  or  streaks  where  the  cells  without  their 
juices  have  dried.  They  attack  stems,  leaves  and  blossoms,  in  the  last 
case  often  blighting  them  and  preventing  the  setting  of  fruit.  On  leaves 
of  plants  the  under  surface  appears  in  most  cases  to  be  the  preferred 
place  of  attack  and  the  insects  do  not  move  about  much.  With  grasses 
and  cereals  the  stems  as  well  as  the  leaves  suffer,  thus  checking  the  growth 
of  the  top,  and  in  some  cases  the  kernels  of  growing  grain  are  also  fed 
upon.  Some  species  live  under  loose  bark  and  a  few  have  been  reported 
as  feeding  upon  other  insects.  In  many  cases  the  injury  caused  by  these 
insects  is  very  serious. 

In  one  section  (Suborder  Terebrantia)  the  female  has  an  ovipositor 
with  which  she  saws  slits  in  the  epidermis  of  plants,  placing  an  egg  in 
each  slit.  In  the  other  section  (Suborder  Tubulifera)  there  is  no  ovi- 
positor and  the  eggs  are  laid  upon  the  surface  of  the  food  material.  The 
larvae  considerably  resemble  the  adult.  After  from  two  to  four  molts 
they  leave  their  food  to  find  some  more  protected  place  and  there  molt 
again,  at  which  time  wing  stubs  appear  and  other  changes  can  be  seen. 
Another  molt  and  now  the  insect  becomes  quiet  unless  disturbed,  not 
feeding,  and  marked  changes  become  evident,  bringing  it  more  nearly 
like  the  adult,  and  the  completion  of  these  changes  is  followed  by  a  molt 
which  produces  the  adult  itself.  This  is  more  than  a  typical  incomplete 
metamorphosis,  yet  not  entirely  comparable  with  a  complete  one.  It 
may  be  regarded  therefore  as  intermediate  between  the  two. 

In  some  cases  parthenogenesis,  i.e.,  the  production  of  the  next  gener- 
ation by  unfertilized  females,  occurs.  This  is  perhaps  to  some  extent 
determined  by  weather  conditions,  in  this  group.  Parthenogenesis  is 
frequently  present  here  and  there  among  insects  and  will  be  considered 
more  fully  elsewhere.  Driving  rains  are  very  destructive  to  all  kinds  of 
Thrips.  Lady  beetles  and  other  insects  of  several  species  feed  freely 
upon  them. 

The  Wheat  or  Strawberry  Thrips  (Frankliniella  tritici  Fitch). — This 
is  probably  the  most  widely  distributed  species  of  the  group  in  this 
country.  It  feeds  on  wheat,  strawberry,  apple  and  many  other  plants  and 
where  the  blossom  is  attacked  as  in  the  case  of  the  strawberry,  it  is  blighted, 
preventing  the  formation  of  the  fruit  and  producing  the  stunted  struc- 
tures known  as  " buttons,"  instead.  Leaves  attacked  often  curl  and  be- 
come malformed,  the  particular  parts  injured  soon  turning  brown  and 
dying.  In  California  it  is  a  particular  pest  of  alfalfa. 

The  adult  is  about  a  twentieth  of  an  inch  long,  yellowish  in  color.  In 
the  warmer  parts  of  the  South  it  is  more  or  less  active  at  all  seasons  of 
the  year,  but  in  the  North  it  winters  in  protected  places,  many  probably, 
like  other  species,  in  grass  fields  close  to  the  ground. 

The  life  history  in  the  South  requires  about  12  days  but  is  probably 


THE  THYSANOPTERA 


155 


longer  in  the  cooler  temperatures  of  the  northern  states,  and  several  genera- 
tions are  produced  in  a  season. 

Control. — In  general,  spraying  with  nicotine  sulfate  40  per  cent, 
standard  formula,  or  with  kerosene  emulsion,  1  part  in  4  parts  of  water, 
is  a  good  treatment.  Success  with  these  materials,  however,  depends 
largely  upon  the  thoroughness  of  the  application  and  the  number  which 
are  killed.  A  favorite  formula  in  California  consists  of  1J4  gal.  of  com- 
mercial lime-sulfur,  and  3^  fl.  oz.  of  nicotine  sulfate  40  per  cent  in  50 
gal.  of  water,  applied  as  a  spray.  Where  the  adults  are  wintering  in  grass 
fields  and  it  is  practicable,  burning  these  over  will 
destroy  many. 

The  Onion  Thrips  (Thnps  tabaci  Linde.;. — This 
pest  is  present  practically  everywhere  in  Europe 
and  the  United  States,  having  first  been  noticed 
here  about  1872  (Fig.  149).  The  adult  is  about  a 
twenty-fifth  of  an  inch  long,  rather  light  yellow, 
but  turning  brown  as  it  becomes  older.  It  feeds 
on  a  great  variety  of  plants  but  being  the  species 
which  is  particularly  injurious  to  growing  onions, 
is  generally  known  as  the  Onion  Thrips.  The  onion 
leaves  are  whitened  by  the  removal  of  their  juices, 
and  soon  begin  to  bend  sharply  downward,  and 
later  they  may  curl  or  twist  and  even  die,  an  area 
much  affected  in  a  field  being  noticeably  pale 
colored  and  the  plants  stunted,  while  the  bulbs 
make  little  growth. 

•Winter  in  the  North  is  spent  as  the  adult  in 
protected  situations  such  as  in  dead  grass  close  to 
the  ground  or  in  rubbish  left  on  the  field.  In 
spring  the  young  onion  plants  are  attacked  soon 
after  they  come  up,  first  in  the  bud,  later  on  the  leaves,  in  which  the  eggs 
are  laid.  The  life  cycle  from  egg  to  adult  is  influenced  by  the  tempera- 
ture, varying  from  a  little  less  than  3  weeks  to  over  a  month,  and  in 
the  most  southerly  states  the  generations  overlap  so  that  practically  all 
stages  may  be  found  at  the  same  time.  Sometimes  in  the  North  this 
insect  becomes  a  greenhouse  pest  on  roses,  carnations,  cucumbers  and 
tomatoes,  though  the  Green-house  Thrips  (Heliothrips  hcemorrhoidalis 
Douche")  is  most  often  responsible  for  this  injury. 

Control. — Any  methods  of  farming  which  will  reduce  the  oppor- 
tunities for  this  insect  to  pass  the  winter  successfully,  are  of  value.  The 
destruction  of  all  refuse  on  the  field  after  the  crop  has  been  gathered: 
fall  plowing  of  such  fields,  and  burning  over  grass  lands  adjacent  to  them, 
at  the  proper  time  in  the  spring,  are  all  beneficial.  Cultivation  and  fertili- 
zation to  pus.h  the  crop  ahead  early  to  "keep  it  ahead  of  the  thrips"  is 


FIG.  149.— Nymph 
of  the  Onion  Thrips 
(Thrips  tabaci  Linde.), 
greatly  enlarged. 
(From  Britton:  Third 
Rept.  Conn.  State 
Entomologist.) 


156 


APPLIED  ENTOMOLOGY 


also  helpful.  Spraying  the  plants  with  nicotine  sulfate  40  per  cent, 
%  pint.,  4  Ib.  more  or  less  of  soap,  and  50  gal.  of  water  is  a  fairly 
effective  treatment.  Fish-oil  soap  is  better  than  laundry  soap  when 
obtainable,  and  the  amount  to  use  is  determined  by  spraying  a  leaf  with 
the  mixture.  If  the  spray  gathers  together  into  larger  drops,  leaving 
parts  of  the  leaves  dry,  more  soap  is  needed,  for  its  use  is  mainly  as  a 
" spreader"  over  the  leaf  surface.  This  treatment  should  be  repeated 
every  8  or  10  days  as  long  as  the  Thrips  are  present  in  any  abundance, 
until  within  a  month  of  harvesting.  Use  a  fine,  misty  spray  with  con- 
derable  pump  pressure.  Only  thorough  spraying  will  give  effective 
results. 

The  Pear  Thrips  (Tceniothrips  inconsequens  Uzel). — This  insect  was 
first  discovered  in  the  United  States  in  the  central  part  of  California, 


FIG.  150. — Adult  Pear  Thrips   (Tceniothrips  inconsequens  Uzel),  greatly  enlarged.      (From 

U.  S.  D.  A.  Bull.  173.) 

attacking  deciduous  fruit  trees,  particularly  pears,  prunes  and  cherries, 
blighting  the  blossoms  by  the  abstraction  of  their  sap.  Later  it  was  found 
in  British  Columbia,  in  the  Hudson  River  Valley  in  New  York,  and  still 
later  in  Pennsylvania,  Maryland,  and  in  England.  Recently  it  has  been 
learned  that  the  insect  was  first  discovered  in  Bohemia,  feeding  in 
blossoms. 

The  destruction  caused  by  this  pest  in  California  has  been  very  great 
some  years.  The  crop  of  prunes  in  the  Santa  Clara  Valley  alone  has 
been  estimated  as  having  been  reduced  in  the  7  years,  1905  to  1911, 
141,000,000  Ib.  The  injury  is  caused  by  the  feeding  of  the  young  and 
adults  on  leaves,  buds,  flowers  and  fruit,  and  by  laying  eggs  in  the  leaves 
and  fruit  stems  and  also  in  the  small  fruit. 


THE  THYSANOPTERA 


157 


The  dark  brown — almost  black — adults  (Fig.  150)  appear  early  in 
spring,  coming  out  of  the  ground  about  the  time  the  fruit  buds  are  swelling 
and  opening,  and  as  soon  as  these  have  opened  slightly  the  insects  work 
their  way  into  them  and  feed  on  the  most  delicate  parts.  The  eggs  are 
laid  mainly  in  the  young  leaf  and  fruit  stems  and  young  fruit  and  hatch 
on  an  average  after  about  8  days.  The  nymphs  (Fig.  151)  feed  on  the 
leaves  and  young  fruit  forming  a  sort  of  "scab"  on  the  surface  of  the  latter, 
and  remain  on  the  tree  for  2  or  3  weeks,  though  from  the  first  young  to 
appear  to  the  last  young  to  disappear,  may  be 
more  than  2  months.  When  through  feeding 
they  fall  to  the  ground,  which  they  enter  for  a 
varying  distance,  and  there,  after  from  2  to  5  or 
6  months,  they  transform  to  the  last  stage  before 
the  adult,  having  previously  molted  once  under- 
ground. Late  in  the  fall  or  winter  the  final 
molt  produces  the  adults  which  remain  in  the 
ground  till  early  spring. 

This  remarkable  life  history,  quite  unlike 
anything  known  for  any  other  Thysanoptera, 
permits  but  one  generation  a  year,  with  active 
injury  during  only  a  rather  short  period  in  the 
spring. 

Control. — These  insects  can  be  destroyed  by 
spraying  with  Nicotine  sulfate  40  per  cent  used 
at  the  rate  of  1  part  to  800  parts  of  water,  stand- 
ard formula.  Success  with  this  treatment,  how- 
ever, is  entirely  dependent  upon  the  thoroughness 
of  the  application.  The  first  treatment  should 
at  once  follow  the  discovery  of  the  Thrips  upon 
the  swelling  buds  and  should  be  repeated  at  least 
every  2  or  3  days  until  the  buds  are  open  or 
the  Thrips  have  become  very  few.  No  spraying 
should  be  done  from  the  tinte  the  blossoms  open 

until  the  petals  fall.     Then,  if  Thrips  are  abundant  on  the  remains  of 
the  blossoms,  another  treatment  should  be   given. 

The  Citrus  Thrips  (Scirtothrips  citri  Moult.)  is  a  rather  serious  pest 
in  California  and  Arizona.  It  feeds  upon  the  tender  stems,  leaves  and  fruit 
of  citrus  trees,  and  occasionally  also  attacks  the  grape,  apricot  and  other 
plants.  With  seedling  plants  the  leaves  and  buds  are  injured  and 
growth  is  checked.  The  fruit  is  injured  by  scars  and  scabs  caused  by  the 
feeding,  and  greatly  reduced  in  value,  and  some  drops  to  the  ground. 

The  adult  is  one  of  the  smallest  of  the  Thysanoptera,  varying  from 
one-fiftieth  to  one-twentieth  of  an  inch  in  length,  and  is  orange-yellow  in 
color.  The  young  appear  in  April  and  May  and  gather  on  the  leaves 


-Fio.  151. — Nymph  of 
Pear  Thrips,  greatly  en- 
larged. (From  U.  S.  D  A. 
Bur.  Ent.  Bull.  68,  Part  1.) 


158  APPLIED  ENTOMOLOGY 

and  fruit  where  they  remain  until  the  midsummer  hardening  of  these 
parts  leads  most  of  them  to  leave  for  various  other  food  plants,  until 
August  and  September  when  they  return  to  the  citrus  trees  again  and 
lay  their  eggs  in  the  leaves  and  stems  of  the  plant.  These  winter  over 
and  hatch  the  following  spring.  Following  the  production  of  adults 
from  the  hatching  and  development  of  these  eggs,  there  may  be  six  to 
eight  generations  during  the  season  and  all  stages  may  be  present  at 
once  on  a  tree  as  late  as  December,  though  these  die  with  colder  weather, 
leaving  only  the  eggs  to  hatch  in  the  spring.  The  last  stage  before  the 
adult,  during  which  the  insect  is  quiet,  is  passed  in  crevices  of  the  trunks 
or  in  rubbish  under  the  trees,  but  not  in  the  ground. 

-Control. — Spraying,  either  with  lime-sulfur  wash  using  1  part  (if  of 
a  density  of  33°Be.)  in  50  parts  of  water,  or  with  more  water  than  this  if 
the  wash  reads  higher;  or  with  Nicotine  sulfate  40  per  cent,  at  the  rate 
of  1  part  in  800  parts  of  water,  have  given  excellent  results.  The  first 
application  should  be  made  as  soon  as  four-fifths  or  more  of  the  blossoms 
have  fallen,  and  a  second  10  days  to  2  weeks  later.  If  these  two  treat- 
ments have  been  well-timed  and  thorough,  the  third  can  be  delayed  until 
about  3  weeks  after  the  second.  A  fourth  treatment  late  in  August  or 
early  in  September,  if  the  returning  insects  are  very  abundant  on  new 
shoots,  will  aid  much  in  checking  their  increase.  In  all  treatments  the 
application  should  be  very  thorough  and  with  a  pressure  of  at  least  125lb. 
Particular  attention  should  be  given  at  the  second  application  to 
completely  drenching  the  fruit  and  any  tender  leaves. 

In  addition  to  the  species  of  Thrips  given  separate  consideration 
above,  nu  nerous  other  species  are  frequently  of  some  importance. 
Among  these  the  Grass  Thrips  which  sucks  the  sap  from  the  stems  of  the 
lighter  grasses,  turning  them  white  and  killing  them,  thus  causing  "silver 
top"  as  it  is  called;  the  Greenhouse  Thrips  which  attacks  tomatoes, 
cucumbers  and  many  other  plants  in  greenhouses  in  the  North  and  out- 
of-doors  in  the  South,  and  the  Camphor  Thrips  which  is  a  serious  pest 
of  the  Camphor  tree  in  Florida,  are  perhaps  the  most  important. 


CHAPTER  XXII 


THE  CORRODENTIA 

Most  of  the  Corrodentia  are  very  small,  even  tiny  insects,  though 
a  few  giants  of  the  group  found  in  South  America  have  a  wing-spread  of 
about  an  inch.  Some  of  the  group  are  wingless  and  are  most  often 
noticed  as  small,  whitish,  gray  or  brown  specks  running  over  the  leaves 
of  old  books.  These  are  generally  called  Book-lice.  The  winged  forms 
(frequently  called  Psocids,  though  this  name  really  applies  to  the  entire 
group)  when  adult  are  somewhat  larger  and 
are  found  on  tree  trunks,  weathered  fences 
and  other  places  where  lichens  grow,  and 
furnish  them  with  their  food.  In  general 
the  members  of  the  group  eat  animal  or 
vegetable  refuse,  mould,  fungi  and  similar 
materials.  Several  hundred  kinds  are 
known. 

The  body  in  the  Corrodentia  though 
quite  soft,  is  well  developed,  but  the  pro- 
thorax  is  small  and  concealed  in  some  cases 
between  the  head  and  the  mesothorax.  In 
others  it  is  distinct,  but  as  the  meso-  and 
metathorax  are  grown  together  in  those 
cases,  only  two  of  the  three  thoracic  seg- 
ments are  evident.  The  antennae  are  rather 
long  and  slender,  and  the  mouth  parts  are 
for  chewing  but  considerably  different  in 
some  details  from  the  typical  structure. 
The  wings  when  present  are  four  in 
number,  with  very  noticeable  veins,  few  of  which  are  cross-veins.  When 
at  rest  the  hinder  margins  of  the  wings  of  the  opposite  sides  are  brought 
together  over  the  back  of  the  insect  with  their  upper  surfaces  sloping 
down  at  the  sides,  thus  assuming  the  position  of  a  steep  house  roof. 
They  are  often  more  or  less  dusky  or  mottled.  The  tarsi  consist  of  only 
two  or  three  segments.  Ocelli  may  be  present  in  the  adults  but  not  in 
the  nymphs.  These  are  quite  similar  to  the  adults  otherwise,  and  develop 
through  a  series  of  molts  into  the  adult  condition. 

The  group  may  be  characterized  as  follows: 

Small,  soft-bodied  insects  with  or  without  wings  when  adult.     In  those 
having  wings  there  are  two  pairs}  with  prominent  veins:  when  at  rest  they 

159 


FIG.  152.  —  Adult  Booklouse 
about  fifty  times  natural  size. 
(From  U.  S.  D.  A.  Farm.  Bull. 
1104.) 


160 


APPLIED  ENTOMOLOGY 


are  held  at  a  sharp  angle  over  the  body,  hinder  margins  uppermost.  An- 
tennce  long  and  slender.  Tarsi  of  two  or  three  segments.  Ocelli  sometimes 
present  in  the  adult  condition.  Metamorphosis  incomplete. 

This  little  order  contains  few  species  of  much  economic  importance. 
The  wingless  forms — book-lice  (Fig.  152) — found  in  buildings,  eat  the 
paste  and  paper  of  old  books  and  are  also  found  in  birds'  nests  where 
they  find  in  feathers  and  other  organic  debris  their  food.  The  winged 
forms,  frequently  called  Psocids,  are  found  in  various  places,  but  perhaps 
most  frequently  on  the  trunks  of  trees,  generally  in  clusters  and  often  in 
various  stages  of  their  development.  They  have  the  power  of  producing 
silk  and  sometimes  the  clusters  appear  to  be  covered,  at  least  partly,  by 
a  web  of  this. 


FIG.  153. — Adult  Psocids:  a,  side  view  showing  position  of  wings  at  rest;  6,  Psocid 
(Psocus  lineatus)  with  wings  spread.  Both  greatly  enlarged.  (From  Sanderson  and 
Jackson,  Elementary  Entmology:  a,  after  Kellogg:  b,  after  J,  B.  Smith.) 

Some  of  the  book-lice  are  claimed  to  be  able  to  make  a  ticking  sound 
something  like  that  of  a  watch,  and  this  sound  is  often  called  the  "  death 
watch."  Such  a  sound  is  certainly  produced  by  a  small  beetle,  and  the 
possibility  of  the  book-lice  also  being  able  to  make  it  has  been  questioned. 
The  weight  of  evidence  thus  far,  however,  seems  to  favor  this  possibility. 
It  is  heard  chiefly  in  old  houses  at  night  or  when  everything  is  quiet,  as 
a  faint,  rapidly  repeated  tick-tick-tick,  and  is  in  all  probability,  the  call 
of  an  insect  to  its  mate. 

The  winged  Corrodentia  (Psocids,  Fig.  153)  are  not  known  to  be  of 
any  economic  importance.  Where  the  wingless  forms  (book-lice)  be- 
come extremely  abundant  in  buildings,  relief  may  be  obtained  by  a 
thorough  cleaning  of  the  infested  places.  Light  and  air,  particularly 
dry  air,  are  unfavorable  to  them,  and  heating  a  room  to  quite  a  high 
temperature  for  a  few  hours  and  the  exposure  of  all  the  furniture  to 
sunlight  for  a  time  on  a  bright  day  will  generally  free  the  place  from  these 
insects.  All  stages  except  the  egg  appear  to  die  at  the  beginning  of 
winter. 


CHAPTER  XXIII 
THE  MALLOPHAGA 

The  Mallophaga  are  generally  called  bird-lice  but  as  they  feed  by  biting 
off  particles  of  feathers,  hairs  and  scales  of  the  skin,  from  the  animals  on 
which  they  live,  the  name  biting-lice  would  be  better  as  it  would  dis- 
tinguish them  more  accurately  from  a  large  number  of  very  similar 
insects  found  in  many  cases  on  the  same  animals,  which  feed  by  sucking 
the  blood  of  their  hosts,  and  which  are  called  sucking-lice. 


X-K 


FIG.   154. — Samples   of    Mallophaga   or   Biting   Lice,    greatly   enlarged:  hair   lines   show 
actual  length.     {After  Kellogg.) 

The  bird-lice  or  biting-lice  (Fig.  154)  are  very  small  insects  ranging 
from  about  one-twenty-fifth  to  one-tenth  of  an  inch  in  length,  rather 
whitish  in  color,  much  flattened  and  with  an  external  shell  which  is 
unusually  hard  for  such  small  insects.  They  are  wingless  and  are  rarely 
found  off  the  bodies  of  the  birds  and  mammals  on  which  they  live. 
Development  from  the  egg  is  gradual,  through  a  series  of  molts  which 
finally  produces  the  adult. 

The  group  may  be  described  thus: 

Small,  wingless  insects,  usually  with  a  large  head;  mouth  parts  for 
biting.  Body  quite  hard,  flattened.  Parasitic  on  the  bodies  of  birds  and 
some  mammals.  Metamorphosis  incomplete. 

About  fifteen  hundred  kinds  of  Mallophaga  are  known,  most  of  them 
living  on  birds,  where  they  feed  on  feathers  and  skin  scales.  On  mam- 
mals, hairs  replace  the  feathers  as  their  food.  When  abundant,  bare 
areas  on  the  bodies  of  birds  appear  where  the  feathers  have  been  eaten  or 
11  161 


162  APPLIED  ENTOMOLOGY 

have  dropped  out  as  a  result  of  the  feeding  of  these  insects.  Birds  nor- 
mally dust  themselves,  working  the  dust  in  among  their  feathers,  where 
it  is  claimed  it  gets  into  the  spiracles  of  the  lice  and  suffocates  them. 
Apparently  the  greatest  injury  to  the  fowls  does  not  come  from  the  feeding 
on  the  feathers  and  scales,  but  from  the  irritation  produced  by  the 
scratching  of  the  skin  caused  by  the  tarsal  claws  of  the  parasites  as 
they  move  about,  and  this  must  be  quite  severe,  for  birds  considerably 
infested  become  dull  and  act  sick,  and  are  certainly  less  able  to  resist 
disease  than  usual. 

The  eggs  of  the  lice  are  attached  separately  to  the  feathers  or  hairs 
of  the  host,  and  hatch  into  nymphs,  which  on  the  whole  considerably 
resemble  their  adults.  They  feed,  molt,  grow  and  become  adult  in  a 
few  weeks. 


FIG.     155. — Female  Chicken  Body  Louse  (Menopon  biseriaium  Piag.),  greatly  enlarged. 
(From  U.  S.  D.  A.  Farm.  Bull.  801.) 

Though  these  insects  are  widely  distributed  on  many  kinds  of  birds 
and  on  a  number  of  mammals,  they  are  of  importance  from  an  economic 
standpoint  mainly  on  the  domesticated  birds  such  as  chickens,  turkeys, 
geese,  ducks  and  pigeons,  though  occasionally  dogs,  cattle  and  horses 
become  infested. 

Seven  different  kinds  of  biting-lice  are  fairly  common  on  domestic 
fowls.  Of  these,  some  prefer  the  head  for  their  location,  others  the  body 
(Fig.  155),  etc.,  though  not  found  exclusively  in  those  locations.  Four 
kinds  are  often  present  on  turkeys  and  quite  a  number  occur  on  geese 
and  ducks.  Pigeons  and  guinea  fowls  have  several  species. 


THE  MALLOPHAGA  163 

Control  of  Lice  on  Poultry. — Various  methods  of  control  for  poultry 
lice  are  in  use,  but  in  most  cases  at  least,  the  best  one  is  the  use  of  sodium 
fluorid,  dry  or  dissolved  in  water.  Either  the  commercial  or  the  chemi- 
cally pure  grade  can  be  used  but  the  commercial  is  somewhat  easier  to 
work  with,  particularly  for  dusting  the  fowls. 

The  first  step  in  treatment  is  to  shut  up  all  the  fowls.  Then  each 
bird  is  taken  and  while  being  held  either  by  the  wings  or  legs  with  one 
hand,  pinches  of  the  powder  are  placed  in  among  the  feathers,  "one  on  the 
head,  one  on  the  neck,  two  on  the  back,  one  on  the  breast,  one  below  the 
vent,  one  on  the  tail,  one  on  each  thigh,  and  one  scattered  on  the  under- 
side of  each  wing  when  spread."  For  young  birds  dusting  rather  than 
dipping  is  advisable. 

If  dipping  is  preferred  for  the  older  birds,  use  warm  water  in  a  tub, 
measuring  the  water  put  into  the  tub  and  adding  from  %  to  1  oz.  of 
the  commercial  fluorid  (or  %  oz.  of  the  chemically  pure  fluorid)  to  each 
gallon  of  water.  Dip  the  birds  in  this,  holding  the  wings  over  the  back 
with  one  hand  and  ruffling  the  feathers  with  the  other,  below  the  surface 
of  the  water.  Then  duck  the  head  of  the  bird  once  or  twice,  take  it  out 
of  the  water,  let  it  drain  for  a  moment  and  then  let  it  go.  After  a  little 
experience,  three-quarters  of  a  minute  per  bird  will  be  an  ample  amount 
of  time  for  this  treatment. 

The  water  in  the  tub  will  be  reduced  in  quantity  of  course,  by  use, 
and  more,  having  the  proper  amount  of  fluorid  dissolved  in  it  should  be 
at  hand  to  add  from  time  to  time. 

Whether  the  sodium  fluorid  treatment,  which  has  only  recently  been 
discovered,  will  give  satisfaction  for  the  treatment  of  biting  lice  on  mam- 
mals cannot  be  stated.  Heretofore,  washing  an  infested  animal  with 
kerosene  emulsion  has  been  advised. 

Boxes  of  road  dust,  available  in  poultry  houses  during  the  winter 
months  for  the  birds  to  dust  themselves  in,  are  desirable.  Formerly 
used  to  actually  aid  the  birds  in  freeing  themselves  of  lice,  they  now  act 
as  indicators  that  lice  are  present  and  that  treatment  should  be  given 


CHAPTER  XXIV 


THE  ANOPLURA 

These  insects  are  the  sucking  lice  which  attack  mammals,  and  mam- 
mals only.  They  are  small,  wingless  insects  from  about  one  twenty-fifth 
to  one-fourth  of  an  inch  in  length,  and  with  mouth  parts  for  sucking.  The 
head  is  usually  rather  pointed  in  front  and  is  often  joined  to  the  thorax 
by  a  distinct  neck  which  permits  its  free  movement.  The  distinction 
between  thorax  and  abdomen  is  less  evident,  the  constriction  there  being 
practically  non-existent.  The  legs,  which  join  the  thorax  well  out  on  its 
sides,  are  constructed  for  climbing  and  grasping,  and  each  ends  in  a 
single  claw,  so  placed  with  reference  to  the  rest  of  the  leg  that  it  can 
tightly  grasp  a  hair,  the  claw  on  one  side  and  the  tibia  on  the  other. 
The  eyes  are  rudimentary  or  absent  in  some  cases. 

The  group  may  be  defined  as: 

Small,  wingless  insects  with  sucking  mouth  parts,  feeding  on  the  blood 
of  mammals.  Eyes  present  or  absent.  Tarsi  each  with  one  claw.  Meta- 
morphosis incomplete. 


FIG.  156. — Samples  of  Anoplura  or  Sucking  Lice,  greatly  enlarged.     (After  Dalla  Torre.) 

Anoplura  (Fig.  156)  occur  on  man,  monkeys,  domestic  animals,  rats, 
mice,  rabbits,  squirrels,  the  elephant,  etc.,  and  one  genus  is  found  on  the 
seal.  The  mouth  consists  of  a  flexible  proboscis  which  may  be  drawn 
in  or  pushed  out,  turning  inside  out  as  it  goes  and  exposing  some  chiti- 
nous  hooks  which  attach  themselves  to  the  skin  of  the  host.  Lodged 
in  the  head  are  two  long,  slender,  sharp-pointed  structures  called  stabbers, 
one,  possibly  both,  apparently  double  in  nature  but  more  or  less  fused, 
and  so  placed  as  to  form  a  canal  between  them  through  which  saliva  may 

164 


THE  ANOPLURA 


165 


be  injected  into  the  wound  they  make.  These  stabbers  are  forced 
through  the  skin  within  the  area  encircled  by  the  proboscis,  saliva  is 
forced  into  the  wound  and  after  a  few  moments  feeding  begins,  the  blood 
of  the  host  being  pumped  into  the  body  of  the  louse. 

Eggs  or  "nits"  are  laid  singly,  attached  to  the  hairs  of  the  host  or  in 
some  species,  to  the  fibres  of  the  clothing.  They  hatch  in  from  1  to  2 
weeks,  according  to  the  species  and  the  temperature,  but  when  the 
latter  remains  low,  as  where  the  eggs  do  not  feel  the  effects  of  the  warmth 
of  the  host,  they  will  not  hatch  (at  least  with  the  lice  infesting  man). 
The  nymph  stage  probably  requires  8  to  10  days,  though  practically 
nothing  is  known  of  the  development  except  with  the  lice  attacking 
man.  Several  hundred  eggs  are  usually  laid  by  each  female  during  a 
period  of  nearly  a  month,  so  that  a  heavy  infestation  becomes  possible 
in  quite  a  brief  time. 

The  Anoplura  is  a  small  group  of  insects,  probably  only  about  a 
hundred  species  being  known.  They  were  formerly  considered  degener- 
ate Hemiptera,  but  with  the  division  of  the  

old  Order  Hemiptera  into  separate  orders — the 
Hemiptera  in  a  more  restricted  sense  and  the 
Homoptera — it  has  seemed  more  logical  to  regard 
the  Anoplura  as  also  an  Order,  most  closely  re- 
lated to  these,  but  still  sufficiently  different  to 
entitle  it  to  ordinal  rank. 

The  Human  Body  Louse  (Pediculus  humanus 
L.). — This  pest  (Fig.  157),  which  during  the 
European  war  also  received  the  common  name 
"cootie,"  is  now  generally  regarded  as  being  of 
two  races,  the  head  louse  (formerly  called  Pedi- 
culus capitis)  which  is  found  chiefly  on  the  head, 
and  the  body  louse  (formerly  Pediculus  vestimenti 
or  P.  corporis)  found  mainly  on  the  clothing, 
rather  than  different  species,  but  the  races  differ 
somewhat  because  of  different  conditions  under 

which  they  live.  This  insect  under  ordinary  conditions  of  cleanliness 
can  be  easily  controlled,  but  in  camp  life  finds  an  opportunity  to  increase, 
often  almost  without  possibility  of  being  checked. 

Under  ordinary  conditions  a  simple  treatment  for  the  race  living  on 
the  head  is  to  wash  thoroughly  with  tincture  of  larkspur,  which  can  be 
obtained  of  a  druggist,  and  repeat  this  two  or  three  times  at  intervals  of 
about  a  week.  For  the  race  living  on  the  body,  treatment  is  somewhat 
different,  as  the  pests  are  largely  on  the  clothing,  reaching  across  from  this 
to  the  skin  to  feed.  Here  boiling  all  clothing  which  can  be  so  treated, 
dry  heating  the  rest  to  130°F.  for  J^  hr.  and  taking  a  hot  bath  will  usu- 
ally be  sufficient. 


FIG.  157.— Human  Body 
Louse  (Pediculus  humanus 
L.)  about  eight  times 
natural  size.  (From 
Bei  lese.) 


166  APPLIED  ENTOMOLOGY 

Rather  recently  it  has  been  discovered  that  the  lice  of  man  are  con- 
cerned in  the  transmission  of  Relapsing  fever,  Trench  fever,  and  that 
terrible  disease  Typhus  fever.  It  does,  not  at  present  seem  that  the 
causal  agents  of  the  first  two  of  these  are  actually  transferred  to  man 
by  the  feeding  of  the  infested  lice,  but  rather  that  these  agents  are  present 
in  their  bodies  and  feces,  and  that  by  scratching  parts  irritated,  fluids  from 
crushed  lice  or  the  feces  get  rubbed  into  the  irritated  areas,  are  able  to 
enter  the  body,  reach  the  blood  and  begin  the  disease.  This  also 
appears  to  be  true  in  the  case  of  Typhus  fever,  but  here  inoculation  by  the 
feeding  of  the  lice  also  seems  probable.  In  some  cases  where  scratching 
does  not  occur  but  where  Relapsing  or  Trench  fever  nevertheless  develops, 
it  is  probable  that  the  feces  get  into  the  feeding  wounds  and  in  that  way 
cause  the  disease. 

The  Crab  Louse  (Phthirus  pubis  L.). — This  louse  is  quite  different 
in  appearance  from  the  last,  being  smaller,  shorter,  broader,  and  with 

its  legs  projecting  outwardly  near  together 
(Fig.  158).  The  fore  legs  are  slender  but 
the  others  are  stout  and  each  has  a  powerful 
serrated  claw  which  shuts  against  a  pro- 
jection of  the  preceding  segment  of  the  leg 
in  such  a  way  as  to  give  a  very  firm  grip 
on  a  hair.  This  insect  is  found  primarily 
on  the  hairy  parts  of  the  body  except  the 
head,  but  in  exceptional  cases  it  may  be 
found  there  also.  It  holds  onto  the  hairs 
while  feeding  and  in  moving  about  always 

FIG.  158. — Human  Crab  Louse  .  .    .     .  .     .  ..  ,••••, 

(Phthirus  pubis  L.)  about  twelve  holds  tightly  to  hairs  on  one  side  until  it 
times  natural  size.  (From  Beriese.)  has  obtained  a  grasp  on  others  on  the 

other  side.  This  gives  it  a  sideways  move- 
ment which  is  responsible  for  its  common  name.  Its  life  history  is 
much  the  same  as  in  the  other  species. 

Washing  thoroughly  with  tincture  of  larkspur  as  for  the  head  louse 
is  usually  an  effective  treatment.  An  ointment  made  of  4  parts  of  crude 
naphthaline  mixed  with  1  part  of  soft  soap  rubbed  on  the  undercloth- 
ing in  the  infested  region  has  also  been  found  to  be  a  very  successful 
treatment. 

Lice  on  Domestic  Animals. — These  are  sometimes  serious  in  their 
attacks,  weakening  the  animal  greatly  if  they  are  abundant.  In  the 
treatment  of  these  pests  it  should  be  borne  in  mind  that  poisonous 
materials  cannot  be  used  because  of  the  danger  coming  from  the  animals' 
licking  themselves.  Various  substances  have  been  used  for  live  stock, 
such  as  15  per  cent  kerosene  emulsion  scrubbed  on  the  skin;  washing 
with  potassium  sulfid,  using  from  2  to  4  oz.  per  gallon  of  water  according 
to  the  size  and  vigor  of  the  animal;  the  application  of  a  mixture  of  sulfur 


M 


THE  ANOPLURA  167 

1  part,  lard  4  parts,  rubbed  over  the  body,  or  washing  with  dilute  car- 
bolic acid  using  1  part  of  the  acid  in  30  parts  of  water.  The  most  usual 
treatment  for  cattle  lice,  however,  is  by  the  use  of  stavesacre  (Delphin- 
ium) seeds.  Four  ounces  of  these  seeds  and  1  oz.  of  white  hellebore  are 
boiled  in  a  gallon  of  water  until  only  2  qt.  remain.  This  is  then  applied 
with  a  brush  to  the  animals.  It  may  need  to  be  repeated  if  more  lice 
appear,  showing  that  eggs  or  some  of  the  lice  escaped  the  first  application. 
Raw  linseed  oil,  applied  with  a  brush  has  recently  been  recommended  as 
an  alternative  treatment,  the  material  for  one  animal  costing  about  five 
cents. 

The  relation  of  insects  to  disease  as  has  been  brought  out  above, 
where  lice  serve  to  convey  the  germs  or  parasites  causing  illness  to  man, 
is  one  of  the  newer  subjects  in  Entomology  but  one  which  has  been  shown 
to  be  of  great  importance.  Medical  Entomology  is  already  a  large  field 
upon  which  much  has  been  written,  and  yet  one  about  which  little  is 
probably  known  in  comparison  with  its  actual  size. 


CHAPTER  XXV 
THE  HEMIPTERA 

The  Hemiptera  is  a  large  group  containing  many  insects  which  are 
always  injuriously  active,  and  many  more  which  occasionally  become  so. 
They  vary  greatly  in  size,  some  being  minute  while  others  may  attain 
a  length  of  four  or  five  inches.  They  are  most  numerous  in  species  in 
the  warmer  portions  of  the  globe,  but  an  abundance  of  individuals  in 
colder  regions  results  in  making  them  extremely  common  everywhere. 

Most  Hemiptera  have  the  dorsal  surface  of  the  body  rather  flattened, 
though  there  are  many  exceptions  to  this  statement,  and  the  wings  when 
not  in  use  rest  upon  this  surface.  The  wings  are  nearly  always  present, 
four  in  number,  and  the  basal  half,  or  sometimes  more,  of  the  front 
pair  is  thickened  and  horny,  resembling  the  elytra  of  beetles.  The  outer 
end,  however,  is  membranous  and  veins  traverse  this  portion,  so  that  the 
fore  wings  are  appropriately  called  hemielytra.  The  membranous  part 
of  one  wing  largely  overlaps  that  of  the  other  when  they  are  at  rest.  In  a 
few  families  the  difference  in  the  texture  of  the  two  portions  is  not  very 
perceptible  but  in  most  cases  it  is  plainly  evident.  The  hinder  wings  are 
entirely  membranous  and  when  not  in  use  are  concealed  beneath  the 
others. 

The  body  of  the  Hemipteron  with  few  exceptions,  shows  no  constric- 
tion at  the  junction  of  thorax  and  abdomen  and  is  usually  widest  at  the 
hinder  end  of  the  prothorax.  The  attachments  of  the  wings  behind 
this  do  not  occupy  anywhere  near  all  of  the  width  of  the  body,  and 
directly  behind  the  pronotum,  between  the  wings,  the  space  is  taken 
up  by  a  rather  large,  usually  quite  triangular  plate  called  the  scutellum. 
In  some  families  this  becomes  greatly  enlarged,  covering  more  or  less 
of  the  dorsal  surface  of  the  body  from  the  pronotum  back,  and  in  such 
cases  the  wings  in  closing  slip  under  this  so  that  little  besides  their  costas 
show. 

Hemiptera  are  sucking  insects  (Fig.  159),  obtaining  their  food  by 
piercing  the  surfaces  of  plants  or  animals  and  drawing  into  their  own 
bodies  the  sap  or  blood.  The  mouth  parts  in  the  group  have  been  identi- 
fied with  those  of  chewing  insects,  but  they  have  been  greatly  modified  to 
form  a  beak  or  rostrum  which  is  attached  to  the  front  of  the  underside 
of  the  head.  The  details  of  structure  of  the  rostrum  differ  in  different 
Hemiptera  but  agree  in  general  plan  (Fig.  160).  The  outside  of  the 

168 


THE  HEMIPTERA 


169 


rostrum  is  a  sheath  which  appears  in  the  main  to  be  derived  from  the 
labium  or  hinder  lip  of  the  chewing  insect,  being  much  elongated,  and 
its  sides  rolled  forward  to  meet  or  almost  meet  in  front,  forming  a 
tube.  The  front  part  of  this  tube,  however,  near  the  head,  seems  not  to 
be  formed  by  the  labium,  leaving  open  a  somewhat  triangular  place 
and  the  labrum  or  front  lip  appears  to  have  grown  downward  to  more  or 
less  completely  close  up  this  portion  of  the  sheath.  Within  the  tube 


^la 


FIG.  159.  FIG.  160. 

FIG.  159.  —  Side  view  of  a  Squash  Bug  (Anasa  tristis  De  G.)  showing  the  rostrum, 
and  its  attachment  to  the  front  of  the  head.  Some  of  the  mouth  parts  usually  within  the 
sheath  have  been  pulled  out  and  show  in  front  of  it.  Rather  more  than  twice  natural  size. 
(Original.) 

FIG.  160.  —  Diagram  of  a  cross-section  of  rostrum  of  a  Squash  Bug:  la,  labium;  md, 
mandible;  mx,  maxilla;  Sa,  tube  carrying  saliva  to  the  wound;  su,  tube  through  which  the 
food  is  drawn  into  the  body.  (Modified  from  Tower,  Am.  Ent.  Soc.  Am.  VI,  1913.) 


thus  formed  lie  the  mandibles  and  maxillae  which  have  become  trans- 
formed into  long  and  slender  bristles  with  pointed  tips.  The  surfaces 
of  the  maxillae  which  face  each  other  have  so  changed  their  outline  as  to 
form  two  gutters  or  troughs  and  when  the  maxillae  are  pressed  together 
as  is  the  case  in  the  living  insect,  each  gutter  of  one  side  coincides  with  the 
corresponding  one  of  the  other  to  form  two  tubes,  half  of  each  being 
contributed  by  each  maxilla.  The  more  anterior  of  the  tubes  is  for  suck- 
ing the  nourishment  obtained,  into  the  bug,  while  the  other  is  for  inject- 
ing saliva  into  the  wound.  The  mandibles  lie  beside  the  maxillae  and 
seem  to  function  chiefly  as  piercing  organs. 

In  feeding,  the  tip  of  the  rostrum  is  brought  into  contact  with  the  sur- 
face of  the  object  to  be  fed  upon  and  the  tips  of  the  mandibles  and  maxillae 
are  then  driven  into  it  until  sap  or  blood  as  the  case  may  be,  is  reached. 
Then  saliva  is  forced  into  the  wound  and  this  seems  to  be  irritating  or 
even  poisonous  in  its  nature  and  its  presence  in  the  wound  causes  (in 
animals  at  least)  an  increased  flow  of  the  body  fluids  to  that  point. 
Assured  thus  of  a  sufficient  supply  of  food,  sucking  it  into  the  body  of 
the  insect  is  then  begun. 

The  eggs  of  Hemiptera  are  laid  under  greatly  differing  conditions. 
Some  are  inserted  in  twigs  or  stems;  others  are  laid  either  singly  or  in 


170 


APPLIED  ENTOMOLOGY 


clusters  on  leaves,  twigs  or  in  other  places.  The  eggs  themselves  vary 
much  in  appearance,  some  being  provided  with  circlets  of  spines,  some 
with  long  filaments  and  some  being  smooth  but  of  unusual  form  or  color. 
They  hatch  into  nymphs  (Fig.  161)  more  or  less  closely  resembling  the 
adult,  which  stage  they  reach  by  a  series  of  molts,  changing  with  each 
molt. 

The  Order  Hemiptera  may  be  characterized  as: 

Insects  which  when  adult  nearly  always  have  four  wings,  the  front  pair 
in  most  cases  partly  horny,  partly  membranous:  with  a  plate  located  between 
the  bases  of  the  wings,  usually  triangular  in  outline,  in  some  cases  covering 
more  or  less  of  the  abdomen  above:  mouth  parts  for  sucking,  and  attached  to 
the  front  end  of  the  underside  of  the  head.  Metamorphosis  incomplete. 


FIG.   161. — Metamorphosis  of  the  Squash  Bug  (Anasa  tristis  De  G.) :  adult  and  nymphs 
of  different  ages,  all  twice  natural  size.      (From  Folsom.) 


Hemiptera  occur  under  almost  every  conceivable  condition  of  life. 
Some  live  in  water,  coming  to  the  surface  only  to  obtain  air:  some  are 
found  on  the  surface  of  the  water  and  some  are  found  on  the  ocean  hun- 
dreds of  miles  from  land.  Most  of  the  group  are  terrestrial,  however,  and 
in  many  cases  are  widely  distributed.  Probably  fifteen  thousand  species 
are  already  known  but  the  group  has  been  little  studied  as  compared 
with  some  of  the  more  attractively  colored  and  marked  orders.  Those 
living  in  water  are  at  least  for  the  most  part,  feeders  on  insects  and  other 
animals  small  enough  for  them  to  capture :  those  which  live  on  the  surface 
are  also  predaceous,  while  of  the  land  forms  some  consume  other  insects 
but  probably  the  larger  number  are  plant  feeders.  The  Hemiptera  are 
the  true  bugs,  the  general  use  of  the  term  "bug"  as  applied  to  all  insects 
being  incorrect. 


THE  HEMIPTERA 


171 


Family  Pentatomidae. — This  group  consists  of  land  forms,  many  of 
them  producing  a  disagreeable  odor  which  has  resulted  in  applying  to 
these  insects  the  common  name  " stink  bugs"  (Fig.  162).  Most  of  them 
suck  the  sap  from  various  plants,  leaving  behind  the  odor  so  often 
noticeable  on  berries.  Others  are  carnivorous,  attacking  caterpillars  and 
sucking  their  juices.  Many  of  them  are  minor  pests  and  potentially 
important  ones,  and  their  fair  size — often  half  an  inch  or  more  in  length- 
together  with  considerable  width,  giving  them  a  broad  surface,  makes 
them  fairly  familiar  objects. 


FIG.  162.  FIG.  163.  FIG.  164. 

FIG.   162. — Pentatomid  Bug  (Euschistus) ,  natural  size.     (Original,) 
FIG.  163. — Adult    Harlequin   Bug    (Murgantia   histrionica  Hahn.),    slightly   enlarged 

(Original.) 

FIG.  164. — Eggs  of  Harlequin  Bug,  slightly  enlarged.     (Modified   from    Essig.    Inj. 

and  Benef.  Ins.  Cal.) 

The  Harlequin  Bug  (Murgantia  histrionica  Hahn). — This  pest, 
native  to  Mexico  and  Central  America,  has  gradually  spread  northward, 
feeding  on  cabbage,  kale,  mustard,  turnip,  radish  and  other  cruciferous 
plants,  and  its  present  northern  limits  are  now  in  New  Jersey  and  Long 
Island,  Ohio,  Indiana,  Wisconsin,  Iowa,  Nebraska,  Colorado,  Arizona, 
Nevada  and  Washington,  though  the  insect  rarely  does  much  injury  so 
far  north. 

.  The  adults  (Fig.  163)  are  about  half  an  inch  long,  black  or  dark  blue 
with  bright  red  or  orange  marks,  the  brilliancy  of  the  colors  making  the 
insects  very  noticeable  and  resulting  in  the  common  names  "calico- 
back,"  "terrapin-bug"  and  perhaps  "fire-bug"  as  well.  They  winter  in 
the  adult  stage  under  rubbish  or  wherever  they  can  find  protection, 
though  in  the  far  South  they  are  more  or  less  active  nearly  all  the  time 
and  there  the  nymphs  are  also  present  then. 

Farther  north  the  bugs  become  active  during  the  early  spring  and 
attack  various  wild  cruciferous  plants  and  lay  their  eggs  (Fig.  164). 
These  are  usually  placed  in  clusters  of  about  12,  in  two  rows,  and  are 
somewhat  barrel-shaped,  white,  with  two  black  rings  around  each,  and  a 
third  ring  on  the  upper  end,  being  both  very  noticeable  and  distinctive. 
They  hatch  in  from  3  to  11  days  according  to  the  temperature  and  the 
nymphs  suck  the  sap  from  the  plants  for  1  to  2  months,  again  according 


172  APPLIED  ENTOMOLOGY 

to  the  temperature,  before  becoming  adult.  When  cabbage,  cauliflower, 
kale,  turnip,  radish,  etc.,  become  available,  the  bugs  go  to  these  and  there- 
after devote  their  attention  to  these  plants  until  late  in  the  fall  when 
various  other  kinds,  such  as  egg  plant,  asparagus,  tomato,  beans,  beets, 
etc.,  may  be  attacked. 

Control. — Insecticides  which  do  not  injure  the  plants  the  bugs  are  on, 
are  not  usually  effective  against  this  pest  and  preventive  methods  have 
thus  far  given  the  best  results.  Planting  a  very  early  crop  of  kale, 
mustard  or  rape,  to  which  the  bugs  when  they  first  become  active  in 
spring  may  be  attracted,  is  a  good  practice,  for  the  insects  seem  to  prefer 
these  to  the  other  plants.  Here  the  bugs  may  be  killed  by  spraying  with 
kerosene,  collected  in  nets  and  destroyed,  or  may  be  burned  with  a  torch. 
The  few  that  may  escape  this  treatment  can  be  picked  by  hand  wherever 
found,  but  if  the  trapping  method  above  is  followed,  few  usually  escape. 

Clean  culture  is  also  helpful.  As  soon  as  the  crops  are  gathered  all 
the  stalks  and  leaves  of  the  plants  on  which  the  Harlequin  bug  feeds 
should  be  gathered  and  destroyed,  both  to  leave  them  no  food  and  to 
remove  possible  places  where  they  might  winter.  Rubbish  which  might 
provide  wintering  quarters  should  also  be  carefully  removed.  Recent 
tests  with  contact  insecticides  show  some  possibility  that  control  by 
these  materials  may  be  obtained,  but  this  subject  has  not  yet  been  suffi- 
ciently investigated  to  warrant  definite  recommendations. 

Family  Cydnidae. — The  bugs  of  this  family  are  usually  of  little  eco- 
nomic importance.  Some  of  them  are  interesting,  however,  as  in  them  the 
scutellum.  usually  quite  small,  becomes  greatly  enlarged,  covering  nearly 
all  of  the  thorax  and  abdomen  behind  the  pronotum.  In  one  genus  the 
insects  are  nearly  circular  in  outline,  very  convex,  having  much  the  form 
of  lady  beetles,  and  are  generally  glistening  black,  in  a  few  cases  with  a 
narrow  line  of  white.  These  are  often  called  " negro-bugs"  and  one 
species  feeds  on  small  fruits  and  leaves  a  disagreeable  odor. 

Family  Coreidae. — Many  of  the  members  of  this  large  family  are  of 
considerable  size  for  bugs,  some  being  over  an  inch  long,  but  their  bodies 
are  much  more  narrow  in  proportion  to  their  length  than  in  the  Penta- 
tomidse.  Some  of  the  southern  species  have  broad,  flat  expansions  of  the 
tibiae,  giving  them  a  curious  appearance.  The  insects  of  this  group  suck 
plant  juices  and  a  number  are  frequently  more  or  less  injurious  to  various 
plants. 

The  Squash  Bug  (Anasa  tristis  De  G.). — The  Squash  Bug  is  common 
almost  everywhere  in  the  United  States  feeding  on  squash  and  pumpkin 
and  sometimes  on  cucumber  and  melon  plants  (see  Fig.  161).  The  adult 
is  a  dark  brown  bug,  very  finely  mottled  with  gray  or  lighter  brown  in 
many  cases,  about  three-quarters  of  an  inch  long.  It  winters  as  the 
adult  under  rubbish  or  in  other  protected  places,  and  appears  in  spring, 
ready  for  its  food  plants  when  these  come  up.  When  the  leaves  of  the 


THE  HEMIPTERA  173 

plants  develop  the  bugs  lay  their  eggs  on  their  under  surface  in  clusters 
which  vary  greatly  in  the  number  of  eggs  composing  them.  The  eggs 
themselves  are  oval  in  outline,  very  convex,  and  being  resin-brown  in 
color  are  very  conspicuous  against  the  green  background  of  the  leaf. 
In  a  cluster  the  eggs  are  not  usually  so  laid  that  they  touch,  but  somewhat 
spaced  apart  in  most  cases.  At  intervals  before  and  during  the  egg- 
laying  period  the  adults  feed  on  the  plants  and  when  they  are  very  abun- 
dant may  seriously  injure  or  in  some  cases  even  kill  them. 

The  eggs  hatch  on  an  average  in  about  10  days  and  the  tiny  nymphs, 
green  and  reddish  in  color,  begin  to  suck  the  sap  from  the  under  side  of  the 
leaves,  at  first  together,  but  scattering  later.  The  reddish  color  of  the 
nymph  quickly  changes  to  black  and  the  green  gradually  becomes  more 
of  a  gray.  Feeding  and  molting  five  times  results  in  the  production  of 
the  adult  after  a  period  of  from  4  to  5  weeks  from  the  time  the  eggs 
hatch,  and  in  the  North  the  adults  feed  on  the  plants  until  fall;  then 
go  into  winter  quarters.  In  the  South  the  longer  seasons  which  permit 
an  earlier  start  in  the  spring  and  the  higher  temperature  which  causes 
the  eggs  to  hatch  more  quickly,  permit  the  production,  in  some  cases  at 
least,  of  two  generations  each  season. 

The  injury  to  the  plants  caused  by  the  spring  feeding  of  the  adult  is 
continued  by  the  sucking  of  the  young.  Where  these  are  plenty,  growth 
is  checked  and  the  crop  reduced.  If  the  plants  are  killed  by  frost  before 
the  nymphs  are  mature,  they  often  attack  the  fruits  in  order  to  obtain 
,the  nourishment  they  need  to  become  adult. 

Control. — Contact  insecticides  are  not  effective  for  the  adult  Squash 
bug,  which  has  an  unusually  thick  shell.  The  usual  methods  for  control  are 
the  removal  as  far  as  possible  of  all  rubbish  and  places  where  the  insects 
can  obtain  protection  during  the  winter;  stimulation  of  growth  of  the 
plants  by  fertilizers  and  cultivation;  protection  of  the  young  plants  by 
fine  netting  until  they  are  so  well  started  that  they  can  thrive  despite  the 
bugs;  traps  of  bark  or  shingles  placed  close  to  the  plants,  under  which  the 
bugs  gather  at  night  and  whence  they  can  be  gathered  and  destroyed 
early  in  the  morning  (this  can  be  begun  even  before  the  plants  are  up) ; 
egg-masses  being  easily  seen  can  be  quickly  found  and  crushed ;  and  while 
the  nymphs  are  small,  spraying  with  Nicotine  sulfate  40  per  cent,  1  part 
in  400  of  water  will  destroy  them.  The  difficulty  in  reaching  the  nymphs 
on  the  under  side  of  the  leaves  with  the  spray,  can  in  part  be  obviated 
by  attaching  the  nozzle  of  the  spray  pump  to  a  piece  of  tubing  connecting 
at  its  other  end  with  the  hose,  and  bent  in  a  loop  so  as  to  give  an  upward 
spray. 

In  the  South  one  or  two  very  closely  allied  species  also  attack  the 
squashes  and  cucurbits  and  may  be  controlled  in  the  same  ways. 

Family  Pyrrhocoridae. — The  insects  of  this  family  superficially  re- 
semble the  Coreids  and  are  of  medium  size.  Only  one  is  of  any  economic 


174 


APPLIED  ENTOMOLOGY 


importance  in  the  United  States,  and  that  in  only  a  few  of  the  Southern 
States  though  it  is  also  injurious  in  some  of  the  West  India  Islands. 
The  Cotton  Stainer  (Dysdercus  suturellus  H.-S.)  as  it  is  called  (Fig.  165), 
feeds  on  cotton,  and  occasionally  the  egg  plant  and  orange  among  culti- 
vated crops.  On  oranges  it  attacks  the  fruit  about  the  time  it  is  ripen- 
ing, puncturing  the  skin  and  thus  hastening  decay.  On  cotton  the  insect 
punctures  the  partly  developed  bolls  and  if  the  attack  is  severe  these 
may  be  destroyed.  If  not,  the  fiber  is  more  or  less  stained,  apparently 
from  the  punctures  in  the  seeds,  reducing  the  value  of  the  cotton 
anywhere  from  5  to  50  per  cent.  As  the  bugs  develop  in  colonies  and 
remain  close  together  for  some  time  and  in  their  early  stages  are  red,  they 


FIG.  165. — The    Cotton    Stainer     (Dysdercus    suturellus    H.-S.):  a,     nymph;    b,     adult. 
Enlarged  about  three  times.      (From  U.  S.  D.  A.  Farm.  Bull.  890.) 


are  easily  located  and  knocked  off  into  dishes  containing  kerosene.  In 
fall  and  spring  they  are  attracted  to  baits,  either  of  cottonseed  or  sugar 
cane,  where  they  can  be  killed  with  kerosene.  The  bugs  also  feed  and 
breed  freely  on  Hibiscus  and  the  Spanish  Cocklebur,  and  the  destruction 
of  these  plants  near  cotton  fields  will  prevent  their  breeding  there  and 
spreading  in  larger  numbers  to  the  cotton. 

Family  Lygaeidae. — There  are  many  kinds  of  insects  in  this  family 
but  nearly  all  are  small,  being  in  most  cases  less  than  a  third  of  an  inch 
long.  A  number  occasionally  injure  various  plants,  and  one — the 
Chinch  Bug — is  one  of  the  worst  half-dozen  pests  in  the  United  States. 

The  Chinch  Bug  (Blissus  leucopterus  Say). — This  little  bug,  less  than 
a  quarter  of  an  inch  long,  feeds  on  all  the  grasses  and  cereal  crops.  It  is 
apparently  a  native  of  tropical  America  which  has  migrated  northward, 


THE  HEMIPTERA 


175 


up  the  Atlantic  Coast,  the  Mississippi  Valley  and  the  Pacific  Coast,  and 
is  now  found  everywhere  south  of  the  St.  Lawrence  River  and  the  Great 
Lakes  and  also  in  southern  Ontario,  Minnesota,  Manitoba,  the  Dakotas 
and  along  the  eastern  slope  of  the  Rocky  Mountains  to  Texas.  It  has 
also  been  found  in  Arizona,  California  and  Washington.  It  is  not  a 
serious  pest  usually  in  the  northeastern  states  and  many  of  the  others, 
but  in  the  Mississippi  Valley  it  often  destroys  crops  valued  at  a  hundred 
million  dollars,  in  one  season. 

The  adult  bug  (Fig.  166)  is  a  tiny  insect  seemingly  incapable  of  causing 
so  much  injury,  but  its  enormous  numbers  make  up  for  its  small  size. 


a  b  c 

FIG.  166. — Different  stages  of  the  Chinch  Bug  (Blissus  leucopterus  Say):  a,  nymph 
in  first  instar;  b,  fourth  instar  nymph;  c,  adult.  All  enlarged  about  nine  times.  (Modified 
from  III.  Agr.  Exp.  Sta.  Butt.  95.) 

Its  body  is  black  or  dark  gray,  with  white  and  therefore  conspicuous 
wings,  each  having  a  single  black  spot.  There  are  two  forms  of  adult, 
however,  one  with  long,  full-sized  wings;  the  other  with  short  wings 
only  partially  covering  the  top  of  the  abdomen.  The  former  occurs  in 
the  Mississippi  Valley  while  the  latter  is  met  with,  together  with  the  long- 
winged  form,  in  the  Atlantic  States  and  to  some  extent  inland  from  there 
along  the  more  southern  of  the  Great  Lakes  to  Illinois. 

The  long-winged  form  passes  the  winter  as  the  adult  in  grass  tufts, 
under  fallen  leaves  or  in  other  places  giving  it  protection.  Corn  shocks 
left  out  over  winter  often  harbor  enormous  numbers.  In  spring  the  bugs 
leave  their  winter  quarters  and  fly  to  the  grain  fields.  Here  they  lay 
their  eggs,  several  hundred  in  number,  on  the  ground  at  the  base  of  the 
plants  or  on  the  roots  just  below  the  surface,  this  process  lasting  about  a 
month.  The  average  length  of  the  egg  stage  is  about  2  weeks  and  the 
young  which  hatch,  suck  the  sap  from  the  plants  for  about  40  days  before 
becoming  adult.  The  nymphs  are  yellow  with  an  orange  tinge  about 
in  the  middle  of  the  abdomen.  This  soon  spreads  over  the  greater  part 


176  APPLIED  ENTOMOLOGY 

of  the  body.  In  later  stages  the  red  becomes  vermilion,  with  a  pale  band 
across  the  front  of  the  abdomen,  the  head  and  prothorax  dusky  and 
before  becoming  adult  the  red  becomes  quite  dark. 

Development,  at  least  for  the  individuals  coming  from  the  later  eggs, 
is  not  complete  before  harvesting  time,  and  to  finish  their  growth  they 
are  obliged  to  migrate  and  find  more  food.  They  accordingly  march  in 
armies,  often  travelling  some  little  distance  on  foot,  and  many  which 
have  already  become  adults,  able  to  fly,  march  with  them.  In  new  feeding 
grounds  development  is  completed  and  the  eggs  for  a  second  generation 
are  laid.  This  generation  appears  to  feed  more  particularly  on  corn, 
kafir  corn,  millet  and  other,  similar  crops,  and  its  members  become 
adult  before  winter,  and  go  into  hiding  until  the  following  spring. 

With  the  short-winged  form,  hibernation- at  a  distance  from  its  food 
plant  is  impossible  because  of  its  inability  to  fly.  This  form  therefore 
winters  in  grass-land  and  begins  its  work  there  in  the  spring.  It  is  a 
question  whether  there  is  more  than  one  generation  a  year  for  this  form. 
Migrations  when  they  occur,  are  of  course  on  foot,  and  corn  is  no  more 
liable  to  be  attacked  than  timothy  or  any  other  grass  crop. 

The  Chinch  Bug  is  particularly  affected  by  weather  conditions, 
dry  weather  being  favorable,  and  wet  seasons  unfavorable.  Dry  weather 
appears  to  induce  migration,  and  a  succession  of  several  dry  years 
favors  a  large  increase  in  their  numbers  and  consequently  of  the  injury 
they  cause.  Rains  during  the  hatching  periods  of  the  eggs  are  very 
destructive  to  the  insect,  and  the  suppression  of  a  Chinch  Bug  attack, 
anticipated  because  of  the  great  abundance  of  the  wintering  bugs,  by 
heavy  rains  at  the  right  time  in  the  spring  is  one  reason  why  these  pests 
are  not  even  more  serious  than  is  the  case. 

A  fungus  (Sporotrichum  globuliferum  Speg.)  generally  called  the 
" Chinch-bug  Fungus"  frequently  attacks  this  insect,  particularly  during 
periods  of  wet,  cool,  cloudy  weather,  and  then  kills  enormous  numbers 
of  them.  In  dry  seasons  it  seems  to  have  little  effect,  and  attempts 
to  control  the  Chinch  Bug  by  placing  individuals  inoculated  with  the 
fungus  in  infested  fields,  while  successful  from  the  experimental  stand- 
point, have  on  the  whole,  hardly  produced  the  results  hoped  for.  It 
is  most  valuable  in  seasons  which  are  dry  during  the  egg-hatching  period 
but  wet  thereafter. 

In  seasons  then,  when  rains  occur  during  the  egg-hatching  periods 
of  the  bugs,  these  and  the  fungus  present  will  usually  prevent  serious 
outbreaks.  In  dry  seasons,  and  particularly  where  there  are  several  in 
succession,  artificial  methods  of  control  must  be  resorted  to. 

Control. — Numerous  methods  of  control  have  been  tested,  with  vary- 
ing degrees  of  success.  Destruction  of  the  adult  bugs  while  wintering, 
has  proved  to  be  an  efficient  treatment  when  conditions  are  such  as  to 
make  it  reasonably  complete.  Burning  over  fields  where  the  bugs  are 


THE  HEMIPTERA  177 

hidden  in  the  grass  has  destroyed  from  about  50  to  75  per  cent  of  them 
in  cases  where  counts  of  the  bugs  could  be  made,  including  as  well,  how- 
ever, areas  covered  with  weeds,  fallen  leaves  and  other  rubbish.  The 
difficulty  with  this  treatment  is  to  get  weather  conditions  such  that  the 
burning  can  be  well  done  and  without  injury  to  the  grass.  Where 
thickets,  hedges  and  other  excellent  hibernating  places  which  cannot  be 
burned  out  are  plenty,  this  treatment,  while  of  value  for  the  bugs  in  the 
areas  where  this  method  can  be  used,  will  of  course  fail  to  reach  those  in 
the  other  locations  and  thus  leave  many  to  appear  in  the  spring. 

Where  Chinch  Bugs  leave  one  field  for  another,  an  old  practice 
has  been  to  plow  a  furrow  across  their  line  of  march  and  dig  an  occasional 
hole  in  the  furrow  into  which  the  bugs,  diverted  from  their  first  direction 
of  march,  might  fall  and  be  destroyed  with  oil  or  other  material.  Bands 
of  tar  or  of  road  oil  across  their  line  of  march  have  also  been  used  with 
some  success,  the  difficulty  with  this  plan  being  in  most  cases  that  the 
band  must  be  placed  on  firm,  hard  ground  or  it  will  soak  in  and  need 
frequent  renewal,  besides  forming  (with  some  materials)  a  surface  film 
on  which  the  bugs  can  cross. 

Crude  creosote  similarly  applied,  has  recently  been  found  to  work 
well.  Though  it  soaks  into  the  ground  it  appears  to  repel  by  its  odor, 
and  the  bugs  reaching  the  band  turn  away  from  it.  Renewal  is  necessary 
only  when  the  odor  becomes  so  slight  that  it  no  longer  acts  as  a  repellent. 
In  1914  the  average  cost  for  material  of  maintaining  a  mile  of  this  band 
during  the  migrating  period  of  the  bugs  was  only  $16.50  at  the  then 
prevailing  price  of  the  creosote. 

When  the  Chinch  Bugs  are  entering  fields  (usually  corn)  at  this 
season,  spraying  the  plants  with  kerosene  emulsion,  Nicotine  sulfate 
40  per  cent  and  soap  solutions  has  been  tested.  The  former  is  liable 
to  injure  the  plants  if  great  care  is  not  given  to  its  application,  but  the 
tobacco  extracts  have  proved  satisfactory.  Soap  alone,  used  at  the 
rate  of  3  oz.  per  gallon  of  water  has  given  excellent  results,  and  while 
the  Nicotine  sulfate,  using  %  fl.  oz.  in  1  gal.  of  water  in  which  J£  oz. 
of  soap  has  been  dissolved,  may  be  the  most  effective,  soap  alone  is 
likely  to  prove  very  satisfactory  and  is  less  costly.  As  the  bugs  enter 
corn  fields  from  elsewhere,  the  spray  need  be  applied  only  to  the  outer 
rows  if  the  invasion  is  observed  in  time. 

The  advice  has  also  been  given  to  cease  planting  corn  in  years 
when  the  Chinch  Bugs  are  liable  to  be  abundant,  raising  instead 
cowpeas,  buckwheat,  stock  beets  or  soy  beans,  on  which  the  bugs  do 
not  feed. 

In  the  case  of  the  short-winged  form  there  is  little  migration,  and 
plowing  and  the  rotation  of  crops  where  the  insects  appear,  seems  to  be 
about    the    only    treatment    available,    and    probably    all    that    will 
be  necessary. 
12 


178  APPLIED  ENTOMOLOGY 

That  insects  like  other  animals  suffer  from  the  attacks  of  various 
diseases,  is  perhaps  not  generally  realized.  Yet  the  list  of  these  diseases 
is  not  a  small  one  and  our  knowledge  of  them  is  still  extremely  limited. 
Some  of  them  are  caused  by  bacteria  and  are  just  as  truly  germ  diseases 
as  are  those  from  which  man  suffers.  Others  are  caused  by  parasitic 
plants  which  in  one  way  or  another  enter  the  body  of  the  insect  and  grow, 
consuming  the  nourishment  they  find  there  and  finally  kill  the  animal, 
usually  making  its  body  hard  and  firm,  or  " mummifying"  it.  A  third 
type  of  disease  is  that  known  as  the  "wilt  disease,"  in  which  neither 
bacteria  nor  fungi  have  been  discovered,  where  the  insect  "wilts"  after  a 
time,  becomes  soft,  and  gradually  decays.  The  producing  cause  of  this 
class  of  diseases  is  still  unknown,  but  they  are  infectious,  spreading  from 
one  individual  to  another,  and  where  the  insects  are  abundant  and 
weather  conditions  are  favorable  they  cause  a  high  mortality. 

Attempts  have  been  made  to  utilize  diseases  for  the  control  of  insect 
pests.  The  Chinch  Bug  has  been  the  subject  of  one  of  the  most  thorough 
of  these  experiments,  the  fungus  already  referred  to  having  been  cul- 
tivated for  the  purpose.  It  was  found  that  by  the  use  of  appropriate 
methods,  cultures  of  the  fungus  obtained  in  the  fall  could  be  grown 
during  the  winter,  and  bugs  inoculated  with  it  in  the  spring  could  be  sent 
out  to  fields  where  the  insects  were  abundant,  and  liberated  there  to 
spread  the  disease.  To  some  extent  this  was  a  success,  but  it  was  soon 
found  that  if  the  inoculated  bugs  were  set  free  during  dry  weather  the 
disease  failed  to  spread  rapidly  enough  to  prevent  great  injury,  while  if 
the  weather  was  wet  the  fungus  was  in  most  cases  already  present  and 
the  addition  of  more  diseased  bugs  at  best  only  hastened  its  spread 
somewhat.  As  a  business  proposition  then,  the  artificial  cultivation 
and  distribution  of  the  fungus  has  been  given  up. 

In  the  case  of  a  bacterial  disease  of  grasshoppers  which  has  at  times 
been  observed  greatly  to  reduce  the  numbers  of  this  insect,  somewhat 
similar  results  have  been  obtained.  In  a  few  instances  some  degree 
of  success  has  been  secured  by  spreading  the  germs,  but  here  the  factor 
of  cannibalism  seems  to  enter  into  the  problem.  With  species  of  grass- 
hoppers which  feed  considerably  on  dead  or  dying  individuals,  there  is 
some  probability  of  successful  treatment  in  this  way,  but  such  species 
are  not  numerous,  and  there  also  appears  to  be  more  or  less  immunity 
to  the  germ  in  some  species. 

The  whole  problem  of  control  by  disease  appears  to  hinge  on  satis- 
factory answers  to  three  questions:  Can  the  disease  be  cultivated  so 
that  a  supply  can  be  obtained  and  continued?  Can  it  be  introduced 
successfully  into  regions  where  it  is  needed  but  not  present?  Will  the 
disease  establish  itself  there  and  become  effective? 

The  answers  to  the  first  two  of  these  questions  are  liable  to  be  affirma- 
tive ones,  though  this  is  not  always  the  case.  The  third  is  the  most 


THE  HEMIPTERA 


179 


difficult  to  determine.  It  may  be  that  the  disease  is  not  already  present 
where  it  is  desired  to  introduce  it  because  conditions  there  are  such  that 
it  will  not  thrive.  Fungous  diseases  at  least  are  influenced  to  a  very 
large  degree  by  the  weather,  most  of  them  thriving  best  in  warm,  moist 
weather  and  if  these  conditions  are  not  present  they  will  amount  to  little. 
At  the  present  time  it  would  appear  .that  the  success  of  artificially 
introducing  diseases  to  control  insect  attacks  is  so  dependent  upon 
weather  conditions  that  man  can  do  little  more  than  supply  the  disease 
and  trust  that  the  needed  kind  of  weather  may  follow.  Unfortunately 
the  very  conditions  under  which  injurious  abundance  of  the  insect  takes 
place,  appears  in  too  many  instances  to  be  those  distinctly  unfavorable 
to  the  spread  of  the  disease. 

Family  Tingididae. — The  insects  (Fig.  167)  of  this  family  are  delicate 
little  bugs,  usually  having  the  pronotum  broadly  expanded  and,  with  the 


FIG.  167. — Example  of  a  Tingidid  Bug  (Gargaphia  solani  Heid.),  enlarged  about  ten  times 
(From  U.  S.  D.  A.  Farm.  Bull.  856.) 

hemielytra,  covered  with  reticulated  marks,  giving  them  something  the 
appearance  of  a  bit  of  lace  and  this  has  been  responsible  for  their  com- 
mon name — lace-bugs.  They  are  rarely  more  than  an  eighth  of  an  inch 
long,  usually  whitish  in  color,  and  suck  the  sap  from  various  plants, 
being  generally  found  on  the  under  side  of  the  leaves.  Their  eggs  are 
placed  on  the  leaves,  generally  at  the  tops  of  small,  brown,  rather  conical 
projections  produced  by  the  bugs,  and  which  somewhat  resemble  places 


180 


APPLIED  ENTOMOLOGY 


where  fungi  project  from  the  leaf  surface.     Several  species  are  occasion- 
ally rather  injurious. 

Family  Miridae. — This  family  until  recently  was  called  the  Capsidse. 
It  contains  a  very  large  number  of  species,  perhaps  more  than  any  other 
family  of  bugs,  all  small,  and  all  feeding  on  plant  juices.  Some  feed  on 
grass;  others  on  succulent  stems;  some  make  a  specialty,  at  least  at  cer- 
tain seasons,  of  sucking  the  sap  from  leaf  and  flower  buds,  distorting 
them  or  even  preventing  their  development.  Sometimes  they  are 
present  in  great  numbers  and  do  much  injury.  Fruit  is  attacked  by  some 
species,  while  it  is  small  and  rapidly  growing,  and  such  attacks  produce 
"  dim  pies"  or  small  depressed  areas,  or  they  may  even  deform  and  thus 
greatly  reduce  the  value  of  the  fruit.  Many  secondary  and  potential 
pests  belong  in  this  family. 

Some  of  the  adults  are  bright  red;  others  red  and  black,  yellow  and 
black  or  other  colors.  In  those  feeding  on  grass,  grayish-yellow  or 

greenish-yellow  is  a  frequent  color.     In  many  cases 

it  seems  that  this  is  in  some  way  connected  with  the 
color  of  their  food,  as  for  example,  some  species 
found  on  the  stems  of  the  red  dogwood  are  them- 
selves largely  red,  though  in  other  cases  it  is  difficult 
to  discover  any  such  correspondence  of  color  between 
the  insect  and  its  food  plant. 

The  Meadow  Plant-bug  (Miris  dolobratus  L.).— 
This  is  apparently  a  species  introduced  from  Europe 
about  a  hundred  years  ago  and  now  found  over  the 
eastern  United  States  and  as  far  west  and  south  as 
Minnesota  and  Kentucky.  It  attacks  cultivated 

The  adult 


FIG.  168. — Meadow 
Plant-bug       (M  iris 

dolobratus  L.),  nearly    grasses  and  is  often  extremely   abundant. 

twice     natural     size.  .  ,1111  i 

(Original.)  (Fig.  168)  is  a  rather  slender  bug  about  two-fifths 

of  an  inch  long,  with  quite  narrow  wings.  It  is 
gray  or  yellowish-gray  with  darker  markings  and  has  long,  black 
antennae. 

The  eggs  are  laid  in  late  summer  and  fall  in  grass  stems,  for  the  most 
part  below  the  cutting  level.  They  hatch  the  following  spring  and 
the  nymphs  feed  on  the  sap  of  the  plant  stems  for  a  little  over  a  month 
before  becoming  adult.  Many  of  the  adults  have  short  wings,  a  similar 
condition  to  that  found  in  the  chinch  bug,  but  here  the  two  forms  mingle 
everywhere,  though  the  short-winged  individuals  may  make  up  as  much 
as  90  per  cent  of  the  total  number. 

Control. — Wintering  in  the  egg  stage  in  grass  stems  suggests  the 
possibility  of  destroying  many  of  the  insects  by  burning  over  grass  fields 
and  particularly  places  where  the  grass  was  not  cut,  during  the  winter 
season.  Early  and  close  cutting  of  the  fields  might  leave  the  insects 
little  to  feed  on.  Fall  pasturing  of  the  fields  and  the  cultivation  of  sod 


THE  HEMIPTERA  181 

land  found  heavily  infested  may  be  of  assistance,  but  so  far,  little  or 
nothing  has  been  done  to  combat  this  pest. 

The  Tarnished  Plant-bug  (Lygus  pratensis  L.). — The  Tarnished  Plant- 
bug  is  widely  distributed,  both  in  Europe  and  this  country.  It  is  about 
a  quarter  of  an  inch  long  (Fig.  169),  shorter  and  broader  in  proportion  than 
the  Meadow  Plant-bug,  and  varies  greatly  in  its  coloration.  The  general 
color,  however,  is  brown,  variegated  with  shades  of  yellowish  and  brown- 
ish and  with  black  spots  in  some  places. 

This  pest  feeds  on  over  50  different  kinds  of  plants  which  are 
of  value  to  man.  The  adults  attack  apple,  pear,  peach,  and  in  fact  all 
fruit  tree  buds,  destroying  or  at  least 
seriously  injuring  them:  small  fruits 
are  often  stunted  or  " buttoned"  by 
them:  flower  buds  of  such  plants  as 
the  chrysanthemum,  dahlia,  peony 
and  aster  are  punctured  and  de- 
stroyed or  malformed:  potato  leaves 
are  often  injured,  causing  tip-burn, 
and  beets,  particularly  sugar  beets, 
have  their  leaves  curled  and  injured. 

~  ,  ,       ,,  FIG.   169.— Tarnished     Plant-bug 

Corn,    wheat,    oats   and  other  gram    (Lygus  watensis  Le) .  Oi  adult.  6,  nearly 

and    grass    Crops  are    also    injured    by     full-grown  nymph.       Nearly  four  times 
,,  .  .  £      j  TT7'.Li_  natural  size.     (From  U.  S.  D.  A.  Farm. 

this  omnivorous  feeder.     With  young    Bull  856  •> 

peach  trees  in  nurseries  it  causes  the 

trouble  called  "stop-back"  by  killing  the  terminal  buds,  and  it  is  a 

carrier  of  the  fire-blight  of  the  pear,  conveying  the  bacteria  causing  this 

disease  from  infected  to  healthy  trees.     It  is  therefore  a  serious  pest. 

The  insect  passes  the  winter  as  the  adult  and  possibly  as  the  nearly 
full-grown  nymph  also,  in  protected  places,  and  appears  with  the  first 
warm  spring  days  and  attacks  the  buds  of  fruit  trees  and  other  plants. 
Its  eggs  are  inserted  in  leaf  veins  and  stems,  flowers  and  similar  places, 
and  they  hatch  in  about  10  days.  The  nymphs  feed  on  the  juices  of  the 
plants  and  become  adult  in  from  3  weeks  to  a  month.  There  is  therefore, 
time  for  several  generations  in  a  season,  though  the  actual  number  of  these 
does  not  appear  to  have  been  worked  out  and  probably  varies  somewhat 
according  to  the  length  of  the  season  in  different  parts  of  the  country. 

Control. — No  effective  method  of  control  has  as  yet  been  discovered 
for  this  pest,  though  many  have  been  tried.  Spraying  the  plants  infested, 
with  kerosene  emulsion,  Nicotine  sulfate  or  soaps,  early  in  the  morning 
has  been  found  to  kill  some  of  them.  Shields  covered  with  sticky  fly- 
paper, placed  beside  and  over  the  plants  which  are  then  jarred,  captures 
some:  the  destruction  of  all  wild  plants  such  as  asters  and  goldenrod  on 
which  they  feed  and  breed  has  been  advocated ;  and  growing  plants  under 
cheese-cloth;  driving  the  insects  down  the  wind,  and  other  methods  have 
been  suggested,  but  no  really  efficient  control  is  yet  known. 


182  APPLIED  ENTOMOLOGY 

Family  Phymatidae. — The  Ambush-bugs  (Fig.  170)  as  members  of 
this  family  are  called  are  carnivorous  bugs  which  usually  hide  in  blossoms 
to  capture  insects  visiting  there.  They  are  rather  short  and  stout, 
generally  less  than  half  an  inch  long,  and  have  colors  so  combined  on  their 
bodies  as  to  render  them  very  inconspicuous  in  the  flowers.  Their  prey  is 
generally  any  insect  they  can  grasp  with  their  stout  fore  legs,  whether 
it  be  injurious  or  otherwise. 


FIG.  170.  FIG.  171. 

FIG.  170. — Ambush-bug  (Phymata  erosa  wolffii  Stal.):  a,  from  above;  6,  from  the  side, 
showing  the  grasping  front  leg.  Enlarged:  true  length  shown  by  hair  line.  (Modified 
from  Sanderson  and  Jackson,  Elementary  Entomology,  after  Riley,  U.  S.  D.  A.) 

FIG.  171. — Reduviid  Bug,  about  natural  size.      (Original.) 

Family  Reduviidae. — This  large  family  consists  of  "carnivorous  insects 
some  of  which  are  small  while  others  are  considerably  more  than  an  inch 
long  (Fig.  171).  Though  generally  feeding  on  the  blood  of  other  insects 
they  may  occasionally  attack  man  and  in  such  cases  produce  rather 
painful  wounds.  One  species,  most  common  in  the  Southern  States, 
often  enters  houses  and  feeds  upon  the  bedbug,  and  from  this  habit  has 
been  called  the  Masked  Bedbug  Hunter,  the  mask  referring  to  dust  which 
adheres  to  its  rather  sticky  body  before  it  becomes  adult.  Another 
species  in  the  West  and  South  is  occasionally  found  in  beds  where  it 
imitates  the  habits  of  the  true  bedbug.  A  similar  but  different  species 
occurs  in  California. 

The  group  as  a  whole,  preying  as  its  members  do  upon  other  insects 
almost  entirely,  must  be  regarded  as  a  beneficial  one.  The  family  is 
most  abundant  in  the  warmer  climates. 

Family  Cimicidae. — The  Cimicidse  is  a  very  small  group  but  well 
known  through  one  of  its  members,  the  Bedbug.  All  of  the  insects 
belonging  here  are  small,  rather  oval  in  outline,  very  flat,  and  rather 
reddish  in  color.  Birds,  poultry  and  bats  are  attacked  by  species  similar 
to  but  smaller  than  the  Bedbug  and  some  of  these  under  unusual  condi- 
tions, -may  enter  houses  and  attack  man. 

The  Bedbug  (Cimex  lectularius  L.). — This  universally  distributed 
and  well-known  pest  (Fig.  172)  appears  to  have  originated  in  Asia  and 
has  .now  spread  wherever  man  is  found.  It  is  a  small,  flat  insect,  reddish- 
brown  in  color,  about  a  fifth  of  an  inch  long  when  adult,  and  wingless, 


THE  HEMIPTERA 


183 


only  tiny  stubs  of  wings  remaining  to  show  that  it  has  been  derived 
from  winged  ancestors.     It  produces  a  very  noticeable  odor. 

It  is  a  nocturnal  animal,  hiding  during  the  day  in  any  cracks  and 
crevices  it  may  find,  either  in  the  bedstead;  behind  loose  wall  paper  or 
elsewhere.  In  these  places  it  lays  its  eggs,  probably  about  200  in  num- 
ber, these  hatching  in  from  a  week  to  a  much  longer  period  dependent 
upon  the  temperature.  The  nymphs  are  yellowish-white  at  first,  turning 
brown  gradually  with  increasing  age.  Nymphal  life  varies  greatly  in  its 
length,  being  affected  by  the  temperature 
and  food  supply,  but  when  these  are  favor- 
able, about  7  weeks  is  required  to  produce  the 
adult  bug.  Under  less  favoring  circumstances 
the  nymphs  may  remain  unchanged  but  alive, 
for  a  long  period.  The  number  of  genera- 
tions in  a  year  may  therefore  differ  greatly 
under  different  conditions  but  in  warmed 
houses  there  are  probably  at  least  four. 

Where  human  blood  is  not  obtainable  for 
food,  that  of  mice,  rats  or  other  animals 
where  available,  may  be  taken  instead,  and 
living  bedbugs  in  empty  houses  may  perhaps 
be  accounted  for  in  this  way.  Without  food, 
however,  death  within  a  year  is  a  practical 
certainty. 

The  "bite"  of  the  bedbug  is  quite  poison- 
ous to  some  persons  but  not  to  others  and  in 

some  cases  a  sort  of  immunity  is  obtained  by  individuals  continuously 
exposed  to  attacks. 

Bedbugs  are  known  to  be  carriers  of  contagious  diseases  of  man,  such 
as  the  African  relapsing  fever,  Kala-azar,  plague,  and  possibly  leprosy 
also,  but  of  course  the  insect  must  first  become  itself  infected  with  the 
causal  agent  of  the  disease  which  is  very  rarely  the  case,  at  least  in 
the  United  States.  It  does  not  appear  to  transmit  the  diseases  except 
as  the  agents  of  them  by  accident  get  on  the  mouth  parts  of  the  insect. 

Control. — Where  sulfur  can  be  burned  in  a  room,  using  a  pound  for 
each  1,000  cu.  ft.  of  space  for  24  hr.  the  fumes  will  destroy  all  stages  of  the 
bedbug  if  the  room  is  reasonably  tight.  A  thorough  treatment  of  all  places 
where  the  insects  can  hide  and  lay  their  eggs,  with  gasoline,  benzine  or 
kerosene  is  also  successful  if  the  material  penetrates  all  parts  of  the  cracks. 
Corrosive  sublimate  at  least  as  strong  as  a  6  per  cent  water  solution,  can 
be  used  in  the  same  way.  Heating  a  room  or  house  to  from  120  to  130°F. 
in  summer  for  an  hour  or  even  less  has  proved  effective,  as  has  a  tempera- 
ture below  32°F.  continued  for  3  or  4  weeks.  Persons  obliged  to  stop  at 
infested  places  can  usually  obtain  protection  by  dusting  insect  powder 
(Pyrethrum)  between  the  sheets  of  the  bed. 


FIG.  172  . — Adult  female 
Bedbug  (Cimex  lectularius  L.) 
gorged  with  blood.  Greatly 
enlarged.  (From  U.  S.  D.  A. 
Farm.  Bull.  754.) 


184 


APPLIED  ENTOMOLOGY 


Family  Gerridae. — These  insects,  the  Water  Skater^  or  Water  Striders 
(Fig.  173)  as  they  are  commonly  called,  are  often  noticed  during  the 
summer,  skating  over  the  surface  of  quiet  pools  of  water.     Their  bodies 
are  slender  in  most  cases,  less  than  half  an  inch  long,  usually  black  or 
brown,  and  their  long,  slender  legs  project  some  distance  from  the  body. 
A  few  are  shorter  and  broader  bodied.     They  feed  on  any  small  insects 
they  are  able  to  capture  and  winter 
either  under  sticks  or   stones   under    — 
water,  or  in  mud  near  the  edge,  under 
leaves  and  rubbish.     A  few  live  on 
the  surface    of   the   ocean    in    warm 
climates.    They  are  interesting  insects 
to    watch    but    are    of   little    if   any 
economic  importance. 

Family  Notonectidae. — The  Back- 
swimmers  (Fig.  174)  as  they  are 
termed,  live  in  fresh  water.  They 


FIG.  173.  FIG.  174. 

FIG.   173. — Water  Skater  (Gerris  conformis  Uhl.)  about  natural  size.      (Original.) 
FIG.   174. — Notonectids   and   Corixid:  A,    Notonectid    at    the    surface   of   the   water 

showing   under   surface;   A',    swimming   showing   upper   surface;   B,    Corixid   swimming. 

Somewhat  enlarged.     (From  Linville  and  Kelly,  Text-book  in  General  Zoology.) 

are  small,  rarely  more  than  half  an  inch  in  length  and  generally  black 
and  cream-colored.  The  back  has  sloping  sides  something  like  the 
bottom  of  a  boat  and  they  swim  on  their  backs,  propelling  themselves 
by  their  long  legs  which  are  fringed  with  hairs.  They  occasionally 
come  to  the  surface  for  air,  a  supply  of  which  they  carry  down  with 
them  under  their  wings  and  between  the  fine  hairs  covering  the  under 
side  of  the  body.  They  are  carnivorous,  feeding  on  other  small  insects 
but  are  of  little  importance. 

Family  Corixid  ae. — Living  in  the  same  places  and  with  similar  habits 
to  the  Back-swimmers  are  small,  greenish  and  blackish  mottled  insects, 
rather  oval  in  outline  with  heads  somewhat  flattened  in  front,  and  known 
as  Water-boatmen  (Fig.  1742?) .  They  have  long,  fringed,  oar-like  legs 
but  do  not  swim  on  their  backs  and  in  some  way  are  able  to  remain  under 
water  without  coming  up  for  air  for  a  much  longer  time  than  the  back- 


THE  HEMIPTERA 


185 


swimmers.     Like  the  latter  group  they  often  leave  the  water  and  fly  at 
night  and  are  frequently  attracted  to  lights. 

Family  Nepidae. — The  water-scorpions  as  these  insects  are   called, 
live  in  fresh-water  ponds  and  pools.     Two  types  of  form  are  included, 


FIG.  175  FIG.  176. 

FIG.  175. — Water-scorpion  (Ranatra  americana  Montd.)  about  natural  size.    (Original.) 
FIG.  176. — Giant  Water-bug  (Lethocerus  americanus  Leidy),  natural  size.     (Original.) 

one  having  a  long,  slender  body  and  long  legs  (Fig.  175),  the  front  pair  of 
which,  unusually  long,  are  constructed  for  grasping  their  prey  which 
consists  of  small  insects.  In  the  other  type  the  body  is  short,  rather  broad, 
and  flat.  In  both  a  long  tube  consisting  of  two  pieces  which  can  be  pressed 

together  to  form  the  tube,  joins  the  hinder  end  of  the     • 

body  and  while  the  insect  is  an  inch  under  water  in 
some  cases,  this  tube  is  pointed  upward  until  its  tip 
is  out  of  water  and  through  it  the  insect  obtains  air. 
The  slender  forms  lying  quiet  on  the  bottom  of  pools 
resemble  dead  twigs  and  thus  obtain  the  concealment 
needed  to  enable  them  to  get  within  reach  of  their 
food. 

Family  Belostomidae. — These  insects  are  gen- 
erally termed  the  giant  water-bugs.  Some  of  them 
are  the  largest  members  of  the  Hemiptera,  being 
two,  three  or  more  inches  long,  broad,  flat  and  brown 
in  color  (Fig.  176).  They  live  in  fresh  water  and 
feed  on  insects  and  even  small  fish  and  are  thus 
sometimes  injurious  in  the  production  of  food  fishes.  They  fly  by 
night  and  are  frequently  attracted  to  electric  lights,  which  has  led  to 
the  larger  species  being  sometimes  called  " electric-light  bugs."  In  some 
of  the  smaller  species  (Fig.  177)  the  eggs  are  laid  on  the  back  of  the  male 
who  is  thus  obliged  to  carry  them  around  until  they  hatch. 


FIG.  177.— Male 
Belostomid  (Belostoma 
flumineum  Say)  carry- 
ing eggs  on  its  back. 
Natural  size.  (Orig- 
inal.) 


CHAPTER  XXVI 
THE  HOMOPTERA 

The  Homoptera  is  a  large  group  containing  insects  of  many  forms, 
often  showing  little  resemblance  to  one  another.  '  They  suck  sap  from 
plants  through  a  beak,  apparently  very  similar  in  structure  to  that  al- 
ready described  for  the  Hemiptera,  but  it  is  attached,  not  to  the  front  but 
to  the  hinder  part  of  the  under  surface  of  the  head  which  is  very  closely 
joined  to  the  prothorax  so  that  the  beak  frequently  appears  to  arise 
between  the  front  legs.  In  some  instances  where  the  adults  do  not  feed, 
this  structure  is  lacking.  The  wings  are  often  absent  but  when  present 
are  usually  held,  while  at  rest,  sloping  over  the  body  like  a  house  roof. 
They  are  of  the  same  thickness  and  usually,  though  not  always,  trans- 
parent. In  this  group  (except  the  male  scale  insects)  the  metamorphosis 
is  incomplete.  These  facts  may  be  summarized  as  follows: 

The  Homoptera  are  sucking  insects  with  the  beak  (when  present)  arising 
from  the  back  part  of  the  under  side  of  the  head  which  is  very  closely  joined 
to  the  prothorax.  The  wings  (frequently  absent)  are  of  uniform  thickness 
throughout  and  when  not  in  use  are  held  sloping  over  the  body.  The  meta- 
morphosis (except  in  male  scale  insects)  is  incomplete. 

Few  groups  of  insects  show  as  great  differences  in  their  members  as  are 
found  here.  The  cicadas,  often  two  or  three  inches  in  length  and  with  a 
wing  spread  of  four  inches  or  more,  are  among  the  giants  of  the  order, 
while  some  of  the  white  flies  and  scale  insects  are  hardly  more  than 
just  visible  to  the  eye.  Most  of  the  group  move  about  freely,  though 
some  locate  in  one  place  soon  after  they  hatch  and  remain  there 
the  rest  of  their  lives.  In  one  section  the  insect  produces  a  protec- 
tive scale  which  covers  it,  and  beneath  this,  degeneration  of  some 
parts  of  the  body  occurs. 

Many  Homoptera  secrete  a  sweet,  sticky  fluid  called  honey-dew, 
often  in  such  quantities  when  the  insects  are  in  abundance,  that  in  falling 
it  makes  a  noise  like  fine  rain.  Striking  on  leaves,  fruit  or  bark,  it  adheres 
and  dries,  and  a  blackish  fungus  grows  in  it,  giving  to  such  places  a  sooty 
appearance.  This  secretion  appears  to  be  produced  most  abundantly  by 
the  soft  scales,  white  flies,  plant  lice,  jumping  plant  lice  and  some  of 
the  tree  hoppers.  Ants  and  honey  bees  feed  on  the  honey-dew  and 
frequently  visit  the  insects  producing  it,  for  this  food. 

Nine  families  of  Homoptera  are  generally  recognized,  but  four  of 

186 


THE  HOMOPTERA 


187 


these  may,  for  convenience,  be  combined  here.     The  six  to  be  considered 
therefore  are: 


Order  Homoptera 


Cicadas  (Cicadidse). 

Leaf  Hoppers  and  Tree  Hoppers  (four  families). 

Jumping  Plant  Lice  (Chermidae). 

Plant  Lice  (Aphididae). 

White  Flies  ( Aleyrodidse) . 

Scale  Insects  (Coccidae). 


Family  Cicadidae  (The  Cicadas)  .  —  Most  of  the  members  of  this  family 
are  rather  large  insects,  with  bodies  often  two  or  three  inches  or  even 
more  in  length  and  quite  stout  as  well.  Their  wings  are  correspondingly 
large,  and  in  some  species  have  a  spread  of  more  than  six  inches.  Though 
usually  transparent  and  with  prominent  veins  they  sometimes  have 
pigmented  areas  of  various  colors. 

The  adults  place  their  eggs  in  slits  they  make  with  their  ovipositors 
in  twigs.  On  hatching  the  nymphs  drop  to  the  ground  and  make  their 
way  to  the  roots  where  they  feed  on  the  sap.  Metamorphosis  is  more 
nearly  a  complete  one  than  in  the  other  families  of  Homoptera  (except 
the  scales)  ,  the  nymph  having  but  little  resemblance  to  the  adult,  and  the 
last  two  nymphal  stages  are  rather  transitional  in  appearance  between  the 
two. 

The  adult  males  have  vocal  organs  located  on  the  under  side  of  the 
basal  segments  of  the  abdomen  and  covered  by  extensions  backward  of 
the  metathorax.  The  sound  produced  is  often  so  loud,  especially  when 
the  insects  are  abundant,  as  to  be  very  noticeable  and  even  unpleasant. 
No  auditory  organ  has  as  yet  been  discovered  with  certainty,  in  either 
sex. 

Cicadas  are  particularly  inhabitants  of  warm  countries,  though  some 
species  are  abundant  quite  far  from  these  regions.  In  North  America 
they  occur  in  Canada  and  probably  in 
all  the  States  farther  south,  and  are 
found  as  far  north  as  England  in  the 
Old  World.  They  are  often  wrongly 
called  locusts. 

The  Periodical  Cicada  or  Seventeen- 
year  Locust  (Tibicina  septendecim  Say). 
—This  remarkable  insect  is  a  native  of 
North  America.  It  is  found  from  Mass- 
achusetts  to  Northern  Florida  and  west 
to  Wisconsin,  Iowa,  Kansas,  Oklahoma 
and  Texas,  but  is  much  less  important  near  its  northern  limits  than  near 
the  center  of  its  range. 

The  adult  (Fig.  178)  is  about  an  inch  long,  with  a  stout,  black  body, 
orange  eyes,  legs  and  wing  veins.  The  wings  when  at  rest  extend  consid- 


FIG.  178.—  Adult  Periodical  Cicada 
natural  size. 


188  APPLIED  ENTOMOLOGY 

erably  behind  the  body.  In  the  far  South  it  appears  early  in  May  while 
near  its  northern  limits  it  may  be  as  late  as  early  June.  The  insects  are 
usually  in  evidence  for  5  or  6  weeks  and  are  particularly  noticeable  in  and 
near  wooded  areas.  They  suck  the  sap  from  various  trees  but  do  little 
injury  in  this  way.  The  females  lay  their  eggs  in  the  smaller  twigs  of 
trees,  shrubs  and  even  in  herbaceous  plants,  the  oak  and  hickory,  and  in 
the  case  of  fruit  trees  the  apple  seeming  to  be  preferred  for  this  purpose, 
though  more  than  75  kinds  are  attacked.  The  eggs  are  placed  in  slits 
made  in  rows  by  the  ovipositor  and  a  twig  thus  punctured  is  liable  to 
break  off  either  entirely  or  in  part.  The  eggs  hatch  in  6  or  7  weeks  and 
the  nymphs  drop  to  the  ground  and  burrow  to  the  roots  where  they  feed 
until  the  seventeenth  spring  from  the  one  when  they  entered  the  ground, 
most  of  them  being  between  six  and  eighteen  inches  below  the  surface. 

During  the  seventeenth  spring  the  nymphs  burrow  upward,  nearly  to 
the  surface  of  the  ground  but  do  not  usually  come  out  until  ready  for  the 
final  molt  producing  the  adult.  In  some  cases,  however,  upon  reaching 
the  surface  they  construct  earthen  cones  or  chimneys  sometimes  six  or  eight 
inches  high,  within  which  the  burrow  is  continued.  It  is  supposed  that 
these  are  constructed  where  the  cicadas  are  in  moist  places  and  these 
structures  will  bring  the  insects  out  above  the  moisture,  or  that  a  shallow 
soil  enables  them  to  reach  the  surface  before  the  normal  time,  or  unusu- 
ally warm  conditions  hasten  their  start,  and  on  their  arrival  they  are 
not  ready  for  their  final  molt.  Recent  work  indicates  that  length  of 
day  is  a  factor.  Probably  the  last  word  on  this  subject  has  not  yet 
been  said. 

Arrived  at  the  surface  of  the  ground  and  ready  to  molt  for  the  last 
time  the  nymphs  crawl  out  of  their  burrows,  the  greater  number  of  them 
in  the  afternoon  and  evening,  and  make  their  way  to  any  objects  such  as 
a  tree,  stick  or  anything  at  hand,  and  on  these  molt  for  the  last  time  and 
become  the  adults  which  are  ready  for  flight  the  next  morning. 

In  the  course  of  nearly  17  years  of  underground  feeding  it  is  only  natu- 
ral that  some  finding  an  abundant  food  supply  should  be  able  to  gain  a 
little  time  and  appear  during  the  sixteenth  year  as  "  forerunners "  of  the 
main  brood,  and  that  others  with  scanty  food  should  be  delayed  until  the 
eighteenth  season.  These  are  few  in  number,  however.  In  the  South 
is  a  race  with  a  13-year  life,  the  origin  of  which  as  related  to  the  other 
race  is  not  as  yet  explained. 

Though  a  cicada's  life  is  (except  for  the  race  just  mentioned)  17 
years,  they  occur  in  one  place  or  another  every  year,  showing  that  in 
some  way  in  the  past  these  insects  have  diverged  so  that  there  are  now 
17  broods.  Some  places  are  so  unfortunate  as  to  have  several  of  these 
broods  but  though  the  cicada  may  appear  there  every  4  or  5  years,  the 
descendants  of  any  one  of  these  will  not  be  found  until  17  years  have 
elapsed. 


THE  HOMOPTERA  189 

Some  of  the  broods  are  more  abundant  and  widely  distributed  than 
others.  Four  are  of  sufficient  importance  to  be  mentioned.  These  are 
Brood  II,  due  in  1928  from  Connecticut  into  North  Carolina  and  at  a  few 
scattered  points  to  the  west;  the  insects  are  quite  abundant:  Brood  VI, 
due  in  1933,  widely  scattered  over  the  country  but  not  very  abundant: 
Brood  X,  due  in  1936  from  New  York  to  Georgia  and  west  to  Michigan 
and  Illinois  and  at  scattered  points  elsewhere,  this  being  the  most  abun- 
dant brood:  and  Brood  XIV,  due  in  1923,  from  Massachusetts  to  Georgia 
and  west  to  Illinois;  also  an  abundant  brood.  The  important  thirteen- 
year  broods  are :  XIX,  due  in  1924,  from  Iowa  to  Louisiana  and  eastward 
to  the  Carolinas  and  Virginia,  the  largest  of  these  broods :  and  Brood  XXIII, 
due  1928,  from  Missouri,  Illinois  and  Indiana  down  the  Mississippi  Valley 
with  scattered  colonies  here  and  there  to  the  east  as  far  as  Georgia. 
This  is  also  a  large  brood. 

Numerous  enemies  of  the  Periodical  Cicada  are  known,  many  of  them 
being  parasites.  Some  birds  feed  on  them  and  a  fungus  causes  disease 
of  the  adults.  Various  mammals  feed  on  them  as  they  are  coming  out  of 
the  ground. 

Control. — In  forests  nothing  can  be  done  to  control  these  insects, 
but  when  they  appear  -in  sufficient  numbers  in  parks  and  orchards  to 
make  treatment  desirable,  certain  methods  for  preventing  injury  or  for 
the  destruction  of  the  insects  are  feasible.  In  some  cases  collection 
of  the  adults  by  hand  has  paid.  In  others,  spraying  the  tree-trunks 
and  other  objects  on  which  they  rest  while  molting  after  leaving  the 
ground,  aiming  to  hit  as  many  of  the  insects  as  possible,  and  using  a 
strong  kerosene  emulsion  for  the  spray  material  has  proved  quite  effec- 
tive, for  where  the  cicadas  are  not  killed  they  are  crippled  by  the  action  of 
the  particles  of  the  spray  which  strike  them.  This  treatment,  however,  to 
be  successful  must  be  repeated  every  evening  about  sunset  or  very  early 
in  the  morning  before  the  insects  begin  to  fly,  as  long  as  they  continue 
to  come  out  of  the  ground. 

In  the  case  of  fruit  trees  anywhere,  pruning  is  not  advisable  the  spring 
cicadas  are  due  in  that  locality,  until  after  the  eggs  are  laid.  Then, 
pruning  and  burning  the  punctured  twigs  before  the  eggs  hatch  is  desirable. 
In  some  cases  young  trees  suffer  so  severely  that  it  is  not  advisable  to 
set  out  nursery  stock  the  year  before  cicadas  are  due.  Apple  "  whips" 
however,  can  usually  be  safely  planted  the  same  spring  that  the  cicadas 
come,  being  generally  too  small  to  suffer  much  by  the  attacks  of  these 
insects.  Hogs  allowed  to  run  under  trees  known  to  have  cicadas  at 
their  roots  will  kill  many  of  these  pests  as  they  come  to  the  surface  to 
become  adult  in  May  and  June  of  their  seventeenth  year. 

Various  species  of  cicadas  are  common  in  nearly  all  parts  of  the  United 
States.  In  the  East  the  Dog-day  Harvest-flies  (Tibicen  linnei  Sm.  & 
Grsb.,  and  others)  are  often  noticeable  (Fig.  179),  singing  in  the  trees 


190  APPLIED  ENTOMOLOGY 

during  late  July  and  August.  Most  of  these  species  are  somewhat  larger 
than  the  Periodical  Cicada  and  generally  black  and  olive-green,  with  a 
white  powder  or  " bloom"  on  the  under  side  of  the  body.  They  are 
supposed  to  have  about  a  2-year  life  history  and  as  individuals  occur 
every  year,  two  distinct  broods.  A  few  of  these  species  greatly  resemble 
the  Seventeen-year  Cicada  in.  col  or  but  are  smaller,  and  as  they  appear 
more  than  a  month  after  the  latter  have  disappeared,  no  confusion  should 
lead  to  the  belief  that  the  Seventeen-year  Cicada  has  appeared  at  that 
season. 


FIG.  179.  FIG.  180. 

FIG.  179. — Adult  Dog-day  Cicada  (Tibicen  linnei  Sm.  and  Grsb.),  natural  size. 
(Original.) 

FIG.  180. — Tree-hoppers  showing  remarkable  forms  of  the  pronotum.  Enlarged 
about  twice.  (Original.) 

Leafhoppers  and  Treehoppers. — The  four  or  more  families  included 
under  this  heading  contain  a  large  number  of  kinds  of  insects,  many  of 
which  are  extremely  numerous.  Among  them  are  the  lantern-flies  of  South 
America  and  the  candle-flies  of  China  and  India  which  are  quite  large  insects, 
a  number  of  which  at  least  are  luminous.  Some  of  the  insects  here  in- 
cluded are  highly  colored  and  some  secrete  quantities  of  wax  which  is  often 
used  for  candles  and  other  purposes. 

In  one  of  the  families — the  Treehoppers — the  pronotum  is  largely  and  often 
remarkably  developed,  sometimes  giving  these  insects  a  very  grotesque  appear- 
ance. In  this  country,  however,  such  forms  are  not  usual,  the  development  of 
this  section  of  the  body  being  mainly  in  the  line  of  horns  or  humps  and  the 
enlargement  of  this  plate  in  width  or  height  and  in  its  extension  backward  until  it 
covers  most  or  all  of  the  body  (Fig.  180).  The  Treehoppers  of  the  United  States 
are  all  small  insects,  less  than  half  an  inch  long,  and  as  they  sit  on  twigs  their 
peculiar  forms  seem  to  give  them  resemblances  to  buds,  swellings  or  other  charac- 
ters, which  suggests  that  their  odd  outlines  may  be  for  resemblance  to  these 
structures  and  thus  secure  the  protection  from  their  enemies  which  this  would 
give. 

In  general  the  Treehoppers  puncture  the  twigs  of  plants  and  are  injurious, 
though  only  a  few  kinds  are  ever  so  abundant  and  attack  plants  of  such  impor- 
tance as  to  need  consideration. 

Among  these  the  most  common  is  the  Buffalo  Treehopper  (Ceresa  bubalus 
Fab.,  Fig.  181)  found  practically  everywhere  in  the  United  States  except  perhaps 


THE  HOMOPTERA 


191 


in  the  most  southerly  portions,  which  injures  the  twigs  of  fruit  trees  by  its  egg 
punctures  made  in  the  fall.  Two  rows  of  punctures  are  made,  nearly  parallel  to 
each  other,  the  two  rather  resembling  parenthesis  marks, 
and  in  each  a  number  of  eggs  is  laid  which  hatch  the  follow- 
ing spring.  Injury  caused  by  the  feeding  of  the  nymphs  and 
adults  is  slight,  and  in  fact  most  of  the  young  feed  mainly 
on  weeds,  but  the  egg  punctures  (Fig.  182)  cause  distorted 
growth  and  weaken  the  twjg.  Spraying  with  a  fairly  strong 
contact  insecticide  to  destroy  the  nymphs  wherever  these 
are  found,  and  the  destruction  of  all  weeds  like  burdock, 
thistles,  etc.,  near  the  fruit  trees  appear  to  be  the  only 
methods  of  control,  and  the  former  is  rarely  practicable. 

The  Leaf  hoppers  (Fig.  183)  are  extremely  abun- 
dant insects  and  some  of  them  must  do  much  injury 
to  the  grass  crop  as  it  has  been  estimated  that  there 


T 


FIG.  183. — Three  kinds  of  Leaf- 
hoppers  enlarged  about  twice.  The 
left  hand  figure  is  of  a  "spittle  in- 
sect." (Original.) 


FIG.  181.— Adult 
Buffalo  Tree-hopper; 
view  from  above. 
Enlarged  about 
twice.  (Original.) 

are  frequently  as  many  as  one  to  two  millions  of  them  per  acre.  Most 
of  them  are  very  small. 

Some  leafhoppers  have  one  generation  a   year,    others  more,  and 

different  species  appear  to  hibernate  in 

f  different  stages.     In  addition  to  various 

•  «J&.  grasses,  grain,  alfalfa,  clover,  sugar  beets, 

grape,  and  rose,  the  apple,  elm,  willow 
and  other  trees   have    their  juices  ex- 
tracted by  the  feeding  of  these  insects. 
A  group  of    tiny  leafhoppers  known  as 

! '      froghoppers  or  spittle  insects  (See  Fig.  183) 

is  also  included  here.  They  are  common  on 
grasses  and  other  herbaceous  plants  and  also 
on  some  trees  such  as  the  pine,  etc.  The 
nymphs  produce  a  fluid  and  liberate  air  in 

this  in  such  a  way  as  to  form  a  sort  of  froth  or  "spittle"  in  which  they 
live.  They  are  very  abundant  .in  the  northern  states  practically  across 
the  entire  continent,  and  one  species,  the  Grass-feeding  Froghopper 
(Philcenus  lineatus  L.)  is  often  so  common  as  to  wet  the  shoes  of  a  person  who 
walks  through  the  grass  in  June.  The  nymphs  suck  the  sap  from  the  grass  stems, 
withering  and  turning  white  the  upper  parts  of  the  stems  and  the  blossoms,  much 
as  does  the  grass  thrips.  Burning  over  old  grass  fields  where  these  insects  are 
most  abundant,  in  early  spring  will  destroy  many  of  these  insects  in  their  winter 
quarters  close  to  the  ground. 

The  Apple  Leafhoppers  (Empoasca  mali  Le  B.  and  others),  tiny  insects 
about  a  twelfth  of  an  inch  long,  attack  over  fifty  different  kinds  of 
plants  being  generally  most  abundant  on  the  apple,  Norway  maple, 
and  some  kinds  of  oaks  among  the  list  of  trees,  and  on  alfalfa,  clover, 
potato  and  beets.  They  appear  to  occur  in  almost  every  part  of  the 
United  States  and  in  some  sections  of  Canada.  The  adults  are 
generally  pale  green  with  white  markings  on  the  pronotum.  Other 
similar  insects  are  often  present  along  with  these  species,  but  treatment 
for  all  would  be  identical, 


192 


APPLIED  ENTOMOLOGY 


The  apple  leafhoppers  winter  as  the  adults  under  rubbish  and  in  spring 
after  mating  the  eggs  are  laid  in  the  veins  of  the  leaves.  Some  observers 
claim  that  at  least  a  part  of  the  nymphs  in  spring  hatch  from  eggs  laid 
in  apple  bark  in  the  fall.  The  eggs  hatch  in  about  a  week  and  the  nymphs 
feed  for  about  3  weeks,  and  the  adults  of  these  nymphs  lay  eggs  for 
another  generation.  In  the  middle  Atlantic  States  there  are  three 
generations  each  year,  but  this  number  may  be  reduced  near  the  northern 
limits  of  their  range  or  increased  farther  south. 


~  £ 


FIG.  182. — Twigs  showing  injuries  caused  by  the  Buffalo  Tree-hopper  in  laying  its  eggs. 
About  natural  size.     (From.Britton,  Fifteenth  Kept.  Conn.  Agr.  Exp.  Sta.  1915.) 

The  injury  caused  by  these  insects  appears  to  be  a  curling  and  check- 
ing of  the  growth  of  the  leaves  in  some  cases,  particularly  those  near  the 
tips  of  the  shoots  in  the  case  of  young  apple  trees.  Older  trees  suffer 
less  than  nursery  stock. 

Control. — Spraying  thoroughly  with  nicotine  sulfate  40  per  cent, 
1  part  in  1,400  or  1,500  parts  of  water,  with  the  addition  of  soap,  is  a 
successful  treatment  to  use  for  these  insects  if  applied  soon  after  the 
nymphs  appear  in  the  spring,  or  at  least  before  the  leaves  have  curled. 
Good  results  have  also  been  obtained  by  dipping  nursery  stock  in  a 


THE  HOMOPTERA  193 

solution  of  whale-oil  soap  1  Ib.  in  8  gal.  of  water,  or  dissolving  a  bar  of 
common  laundry  soap  in  6  to  8  gal.  of  water  for  the  purpose. 

The  Rose  Leaf  hopper  (Empoa  rosce  L.). — This  European  insect  is  now 
present  practically  everywhere  in  the  United  States  and  is  also  found 
in  Nova  Scotia,  Ontario  and  British  Columbia.  It  is  a  general  feeder 
and  will  probably  attack  most  plants  of  the  family  Rosacese,  but  appears 
to  be  particularly  injurious  to  the  rose  and  apple.  The  adult  is  almost 
as  large  as  the  apple  leafhopper  and  is  creamy  white  to  light  yellow.  It 
lays  its  eggs  during  the  fall  in  the  bark  of  rose  bushes,  apple  trees,  berry 
canes  and  other  plants  and  there  they  remain  until  spring,  when  they 
hatch.  The  nymphs  suck  the  sap  from  the  under  side  of  the  leaves  of 
the  plants,  producing  a  mottled  appearance,  and  as  the  injury  increases 
the  leaves  may  turn  yellow  and  dry  up,  but  they  do  not  curl.  There 
are  two  generations  of  this  insect  a  year,  the  eggs  for  the  second  genera- 
tion being  laid  in  July.  Most  of  the  wintering  eggs  are  deposited  in  rose 
stems. 

Control. — This  insect  is  rarely  of  importance  as  an  apple  pest  but 
rose  bushes  often  suffer  by  the  loss  of  sap  and  the  impossibility  of  their 
injured  leaves  performing  their  proper  functions.  Spraying  infested 
plants  with  nicotine  sulfate  as  for  the  apple  leafhoppers,  as  soon  as  the 
nymphs  are  observed,  is  usually  sufficient  to  prevent  further  injury. 

Many  other  leafhoppers  are  at  times  serious  pests.  The  beet  leaf- 
hopper  in  the  Western  States  in  addition  to  its  injury  to  the  plants  by 
feeding,  transmits  a  " curly  leaf  disease"  and  the  grape  leafhopper  is 
sometimes  so  abundant  that  grape  leaves  in  vineyards  are  turned  brown 
and  much  injured.  The  six-spotted  leafhopper  attacks  some  grains  and 
grasses,  and  other  species  generally  of  slight  importance,  at  times  assume 
prominence.  In  general,  nicotine  sulfate  prepared  as  indicated  above, 
is  an  effective  control  material  for  these  insects  wherever  conditions 
permit  its  use. 

Family  Chermidae. — The  Jumping  Plant-lice  as  the  members  of  this  family 
are  usually  called,  are  very  small  insects  which  feed  on  various  plants  but  are 
rarely  abundant  enough  to  become  of  economic  importance.  One  exception 
to  this  occurs  and  a  consideration  of  that  species  will  also  give  something  of  a 
general  idea  of  the  insects  of  the  group  as  a  whole. 

The  Pear  Psylla  (Psyllia  pyricola  Forst.). — The  Pear  Psylla  is  a  European 
pear  pest  which  seems  to  have  reached  this  country  about  1832  and  is  now 
present  everywhere  in  the  eastern  United  States  at  least  as  far  south  as  Virginia 
and  west  to  the  Mississippi  River,  and  has  also  been  reported  (perhaps  errone- 
ously) from  California.  Where  it  is  abundant  it  is  very  injurious,  seriously 
checking  the  growth  of  the  tree,  so  that  many  of  the  leaves  turn  yellow  and  drop 
off,  as  does  much  of  the  young  fruit,  while.the  entire  vitality  of  the  tree  is  reduced 
and  it  makes  little  or  no  growth. 

The  adult  (Fig.  184)  is  about  a  tenth  of  an  inch  long,  the  body  black  with 
reddish  markings,  and  long  antennae  are  present.  Except  for  this  last  feature 

13 


194 


APPLIED  ENTOMOLOGY 


it  greatly  resembles  a  tiny  cicada.  The  insects  pass  the  winter  as  adults  hiding 
in  crevices  of  the  bark  or  similar  protected  places  and  in  spring  lay  their  eggs 
on  the  twigs,  and  particularly  around  the  bases  of  the  buds.  These  eggs  hatch 
in  from  2  to  3  weeks  according  to  the  temperature.  The  nymphs  (Fig. 
185)  suck  the  sap  from  the  axils  of  the  leaves  and  fruit  stems  and  if  abundant 
gather  around  the  bases  of  leaves  and  fruit  stems  and  spread  to  the  under  surface 
of  the  leaves  themselves.  They  move  about  but  little  and  secrete  large  amounts 
of  honey-dew,  sometimes  so  much  when  they  are  very  numerous,  as  to  cover 
the  leaves  and  branches.  They  are  broadly  oval,  flat  creatures,  yellowish  at 
first  but  blackish  with  reddish  marks  later  and  with  bright  red  eyes.  They 
become  adult  in  about  a  month  and  lay  their  eggs,  this  time  on  the  under  side 
of  the  leaves  or  on  the  leaf  petioles.  These  eggs  hatch  in  a  week  to  10  days  and 
adults  are  produced  in  about  a  month.  There  are  three  or  four  generations  a 
year  in  New  England  and  more  in  the  South. 


FIG.   184.  FIG.   185. 

FIG.  184.— Adult  Pear  Psylla  (Psyllia  pyricola  Forst.)  about  ten  times  natural  size. 
(From  Britton,  Third  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1903,  after  Slingerland.) 

FIG.  185. — Nymph  of  Pear  Psylla,  greatly  enlarged.  (From  Britton,  Third  Rept.  Ent. 
Conn.  Agr.  Exp.  Sta.  1903,  after  Slingerland.) 

Control. — Methods  for  checking  the  injuries  caused  by  these  insects  center 
around  their  control  in  winter  and  early  spring.  Most  of  the  adults  winter 
under  the  loose  bark  of  the  trees  or  in  tufts  of  grass  and  rubbish  near  the  trees. 
Scraping  off  all  loose  bark  and  removal  of  the  rubbish,  followed  during  any 
warm  days  in  November  or  December  by  a  thorough  spraying  of  these  places 
with  nicotine  sulfate,  standard  formula,  will  kill  large  numbers.  It  should  not 
be  cold  enough  for  the  spray  to  freeze  on  the  trees.  In  spring,  just  as  the  clusters 
of  blossom  buds  begin  to  separate  from  each  other,  but  before  the  blossoms 
open,  the  lime-sulfur  wash  diluted  at  the  rate  of  1  part  of  the  wash  to  8  or  9 
parts  of  water  will  kill  the  eggs  and  any  newly-hatched  nymphs.  The  fruit 
spurs  and  the  under  sides  of  the  twigs  should  receive  particular  attention  with 
this  treatment. 

Family  Aphididae  (Plant  Lice  or  Aphids). — This  is  one  of  the  most 
important  groups  of  insects  from  an  economic  standpoint,  as  all  its  mem- 
bers are  injurious,  often  very  abundant,  and  a  species  usually  doing  little 
harm  may  at  any  time  become  a  serious  pest. 


THE  HOMOPTERA 


195 


Aphids  are  tiny,  soft  bodied  insects,  the  largest  being  less  than  a  third 
of  an  inch  long,  generally  with  long  legs  and  antennae,  and  are  of  various 
colors,  green,  black,  various  shades  of  red  and  brown,  white  and  gray 
being  the  most  usual  ones.  Some  are  more  or  less  completely  concealed 
(Fig.  186)  beneath  long,  white  waxy  threads,  giving  them  a  " woolly" 


Fio.  186. — Alder  twig  covered  by  woolly  plant  lice,  the  "wool"  entirely  concealing  their 
bodies.     Somewhat  enlarged.     (Original.) 

appearance;  others  have  a  sort  of  dust  or  " bloom"  like  that  on  a  plum, 
coating  their  bodies;  but  the  majority  (Fig.  187)  are  without  any  covering. 
Many  species  of  aphids  have  a  pair  of  tubes  called  cornicles,  projecting 
upward  from  the  top  of  the  abdomen.  These  were  formerly  believed  to 


Fio.   187. — Portion  of   leaf   showing   plant  lice  clustered  together. 

(Original.) 


Somewhat  enlarged. 


be  the  exit  ducts  through  which  honey  dew,  abundantly  produced  by  the 
insects,  escapes,  but  it  is  now  known  that  this  substance  is  expelled 
through  the  anus,  often  in  such  quantities  that  when  the  insects  are  abun- 
dant it  forms  a  sort  of  fine  rain  which  can  be  heard  falling  on  the  leaves 


196  APPLIED  ENTOMOLOGY 

and  ground.  This  fluid  which  is  sweet  and  sticky  is  eagerly  fed  upon  by 
ants.  Falling  on  twigs  and  leaves  it  dries  there  and  a  fungus  grows  in  it 
turning  it  black,  and  plants  where  aphids  have  been  abundant  often  show 
this  by  their  black  appearance.  Some  plant  lice  produce  galls  within 
which  they  live  for  at  least  a  part  of  their  lives  but  most  of  them  are  not 
thus  enclosed,  living  on  leaves,  twigs,  succulent  plant  stems  or  roots. 

Though  there  are  great  variations  in  the  life  histories  of  different 
aphids,  certain  general  facts  hold  for  most  of  the  group.  In  general,  eggs 
are  laid  in  the  fall,  on  a  food  plant  of  the  species  concerned,  and  these 
hatch  the  following  spring.  The  nymphs  soon  become  full-grown  and  are 
known  as  " stem-mothers"  and  without  fertilization  (there  are  no  males) 
produce  eggs,  or  in  most  cases  living  young  which  like  the  stem-mother 
are  all  females  and  om  reaching  maturity  produce  young  in  a  similar  way. 
The  production  of  young  without  fertilization  of  the  parent  is  not  uncom- 
mon in  insects  and  is  called  parthenogenesis  or  agamic  reproduction.  In 
this  case  the  production  of  these  young  alive  rather  than  from  deposited 
eggs  introduces  the  additional  fact  that  these  insects  are  also  viviparous 
except  in  (generally)  one  generation.  The  number  of  young  produced  by 
each  parent  varies  but  will  perhaps  average  about  ten,  a  few  being  born 
every  few  days,  and  the  number  of  generations  is  variable  but  is  also  likely 
to  be  about  10,  though  the  first  born  young  in  each  generation,  being  a 
week  or  two  older  than  the  last  born  young,  will  gain  enough  time  during 
the  season  to  produce  more  generations  than  the  others.  In  fact,  in 
some  species  a  range  from  8  to  21  generations  for  late  and  early  born 
individuals  has  been  observed,  and  an  average  number  of  28  young  pro- 
duced per  parent,  so  that  the  figures  given  above  may  be  regarded  as 
conservative.  But  even  with  this  moderate  estimate,  allowing  only  10 
young  to  a  generation  and  10  generations  a  season,  the  total  product  from 
a  single  egg  hatching  in  the  spring  and  itself  counted  as  the  first  generation, 
would  be  1,111,111,111,  and  this  would  be  far  below  the  actual  number  in 
most  cases,  were  it  not  for  the  enormous  destruction  of  these  insects  by 
their  enemies  and  by  unfavorable  weather  conditions. 

In  many  species  instead  of  10  young  being  produced  per  female  as  an 
average,  the  number  is  likely  to  be  nearer  a  hundred,  and  in  those  species 
which  also  have  more  than  10  generations  the  total  number  of  individuals 
which  would  theoretically  be  produced  in  a  season  "would  be  sufficient  to 
completely  cover  the  entire  world  with  a  continuous  layer  of  plant 
lice." 

With  such  a  marvelous  reproductive  power  as  this  it  becomes  evident 
that  despite  natural  checks  to  their  increase,  plants  infested  are  liable 
after  a  few  weeks  to  be  entirely  unable  to  provide  food  for  the  hordes  of 
plant  lice  upon  them.  Accordingly  we  find  that  in  most  of  the  genera- 
tions winged  individuals  may  be  produced  so  that  they  can  migrate  to 
other  plants.  Winged  and  wingless  forms  may  therefore  be  found  at 


THE  HOMOPTERA  197 

almost  any  time  during  the  summer,  and  a  wide  distribution  of  the  insect 
is  obtained  in  this  way. 

When  cold  weather  approaches  in  the  fall  a  generation  appears,  con- 
sisting of  both  sexes,  and  the  females  of  this  generation  lay  fertilized 
eggs  which  winter  over  and  hatch  the  following  spring.  In  some  cases 
this  does  not  happen  until  the  second  fall  and  in  a  few  species  at  least, 
sexual  individuals  have  not  been  discovered  and  may  occur  only  at  long 
intervals,  if  at  all. 

Many  aphids  do  not  feed  entirely  on  one  kind  of  plant  but  spend  a 
part  of  the  year  on  one  species,  and  the  rest  on  another.  One  of  the 
species  which  is  injurious  to  the  apple  remains  on  this  tree  from  fall  until 
May  or  June  when  it  migrates  to  grain  and  spends  the  summer  months 
there.  Another  species,  living  on  the  elm  during  the  fall,  winter  and 
spring,  passes  to  the  apple  for  its  summer  residence,  and  a  long  list  of 
aphids  having  alternating  food  plants  is  now  known. 

Plant  lice  suck  the  sap  from  plants  and  often  produce  curling  or  mal- 
formation and  even  wilting  of  the  leaves,  frequently  accompanied  by 
discoloration.  Root-attacking  forms  produce  knots  and  deformities 
affecting  the  health  of  the  plant,  and  young  fruit  becomes  hard  at  the 
attacked  spots  and  remains  small.  The  punctures  aphids  make  often 
enable  the  spores  of  fungi  and  bacteria  causing  plant  diseases  to  enter  the 
plants,  and  they  may  even  transfer  these  from  one  plant  to  another. 
Among  the  diseases  transferred  thus  are  an  oat  blight,  fire  blight  of  the 
pear  and  cucurbit  wilt.  Indirectly  by  the  honey  dew  in  which  spores  can 
live  for  several  days,  it  is  probable  that  the  diseases  can  also  be  widely 
distributed  through  the  agency  of  other  insects  which  visit  and  feed  on 
honey-dew.  In  general  a  year  when  plant  lice  are  abundant  over  a 
large  part  of  the  country  is  certain  to  result  in  great  injury  to  plants  of  all 
kinds  affected  by  these  insects. 

Ants  not  only  gather  the  honey  dew  the  Aphids  produce,  but  in  some 
cases  the  relation  is  closer,  particularly  with  root  feeding  species.  The 
eggs  of  the  corn-root  louse  for  example,  are  gathered  by  ants  in  the  fall 
and  kept  in  their  underground  chambers  during  the  winter.  In  the  spring 
the  ants  place  the  insects  on  the  roots  of  certain  weeds  but  after  the  corn 
has  begun  to  grow  well,  they  transfer  them  to  the  corn  roots  where  they 
visit  them  during  the  summer  to  collect  honey  dew.  (See  page  203.) 

Plant  lice  have  many  enemies  which  destroy  great  numbers  of  them. 
They  are  also  affected  by  the  weather,  cloudy,  wet  periods  being  favor- 
able, though  driving  rains  destroy  many. 

In  general  the  best  control  of  plant  lice  is  obtained  by  the  use  of 
nicotine  sulfate  40  per  cent  used  at  a  dilution  of  from  1  to  800  to  1  to 
1,000  parts  of  water.  Where  this  cannot  be  obtained,  kerosene  emulsion 
or  fish-oil  soap  solutions  rank  next  as  control. 


198 


APPLIED  ENTOMOLOGY 


The  Apple  Aphids. — There  are  three  species  of  plant  lice  which  attack 
the  apple  more  or  less  generally  throughout  the  United  States,  and  a 
fourth  is  injurious  in  some  parts  of  the  country.  In  addition,  a  woolly 
species  feeding  both  on  the  twigs  and  roots  is  of  importance  and  will  be 
treated  later. 

The  three  species  referred  to  are  the  Green  Apple  Aphis  (Aphis  pomi 
DeG.),  the  Rosy  Apple  Aphis  (Anuraphis  roseus  Bak.  and  Turn.)  and 
the  Apple  Grain  Aphis  (Rhopalosiphum  prunifolice  Fitch),  the  latter  until 
recently  believed  to  be  the  same  as  a  European  species  and  generally 
known  therefore,  as  the  European  Grain  Aphis.  All  three  lay  their  eggs 
in  the  fall  on  the  twigs  of  the  apple.  In  the  spring  the  eggs  of  the  Apple 
Grain  Aphis  hatch  a  week  or  10  days  before  those  of  the  other  two.  The 
young  of  all  three  kinds  feed  on  the  buds  and  become  stem  mothers  which 
when  full-grown,  differ  in  appearance. 


FIG.   189. 


FIG.  188. 

FIG.  188. — Green  Apple  Aphis  (Aphis  pomi  De  G.),  stem  mother,  about  eight  times 
natural  size.  (Modified  from  Cornell  Ayr.  Exp.  Sta.  Mem.  24.) 

FIG.  189. — Rosy  Apple  Aphis  (Anuraphis  roseus  Bak.  and  Turn.),  stem  mother,  groutly 
enlarged.  (Modified  from  Cornell  Agr.  Exp.  Sta.  Mem.  24.) 

The  Green  Apple  Aphis  stem  mother  (Fig.  188)  has  a  uniformly  green 
body,  brown  head  and  long,  dark  cornicles:  the  Rosy  Apple  Aphis  stem 
mother  (Fig.  189)  is  greenish  but  blended  with  purplish  brown,  and  the 
cornicles  are  long,  slender  and  dark;  the  body  in  this  case  is  so  dark  as 
to  be  often  described  as  blue:  the  Apple  Grain  Aphis  stem  mothers 
(Fig.  190)  are  yellowish-green,  with,  a  broad  darker  green  stripe  along  the 
middle  above,  from  which  several  side  branches  pass  off,  and  with  rather 
short,  stout,  yellowish  cornicles. 

As  the  leaves  develop  the  lice  feed  on  them  and  in  the  case  of  the 
Rosy  Apple  Aphis  produce  much  curling.  This  is  usually  less  pronounced 
with  the  Green  Apple  Aphis  and  does  not  occur  with  the  Apple  Grain 
Aphis. 

After  a  generation  or  two  on  the  apple,  winged  forms  (Fig.  191)  begin 
to  appear  and  these  migrate  to  summer  food  plants,  except  with  the  Green 
Apple  Aphis  which  remains  an  apple  feeder  throughout  the  year.  The 


THE  HOMOPTERA 


199 


Rosy  Apple  Aphis  migrates  to  species  of  plantain,  particularly  the  nar- 
row-leaved plantain  and  it  is  noticeable  that  the  spread  of  this  plant 
louse  over  the  country  has  closely  followed  that  of  this  introduced  weed. 
The  Apple  Grain  Aphis  migrates  to  small  grains  such  as  wheat  and  oats. 
On  these  summer  food  plants  generation  after  generation  is  produced 
but  in  the  fall  a  migration  back  to  the  apple  occurs  and  here  a  sexual 
generation  appears  and  eggs  are  laid  which  hatch  the  following  spring. 
In  some  cases  the  Apple  Grain  Aphis  may  winter  over  close  to  the  ground 
on  the  grain,  not«returning  to  the  apple.  The  winged  form  of  the  Rosy 
Apple  Aphis  during  the  summer  months  has  a  pinkish  or  reddish  body 
which  has  led  to  its  being  given  its  common  name. 

In  the  middle  West  the  Clover  Aphis  (Aphis  bakeri  Cowan)  has  a 
similar  life  history  to  those  just  outlined,  but  during  the  summer  lives  on 
clovers. 


FIG.  190. 


FIG.  191. 

FIG.  190. — Apple  Grain  Aphis  (Rhopalosiphum  prunifolice  Fitch),  stem  mother,  greatly 
enlarged.  (Modified  from  Cornell  Agr.  Exp.  Sta.  Mem.  24.) 

FIG.  191. — Winged  Migrant  of  Green  Apple  Aphis,  greatly  enlarged.  (Modified  from 
Cornell  Agr.  Exp.  Sta.  Mem.  24.) 

The  chief  injury  to  the  apple  caused  by  these  insects  is  that  their 
feeding  on  the  buds  checks  their  growth.  The  leaves  are  also  curled  and 
growth  is  reduced. 

Control  of  Apple  Plant  Lice. — Destruction  of  the  winter  eggs  by 
sprays  has  not  thus  far  been  very  successful.  The  best  control  known 
at  present  is  to  very  thoroughly  spray  the  trees  just  as  the  buds  are 
beginning  to  open  and  the  eggs  hatch,  with  the  standard  formula  of 
nicotine  sulfate  40  per  cent.  If  an  application  of  lime-sulfur  is  desired 
the  nicotine  sulfate  can  be  added  to  that,  provided  the  soap  be  left  out. 
A  second  application  about  2  weeks  later,  is  sometimes  desirable.  In  case 
nicotine  sulfate  cannot  be  obtained,  kerosene  emulsion,  1  part  to  9 
of  water,  or  fish-oil  soap,  1  Ib.  in  5  to  7  gal.  of  water  may  be  used  instead. 

The  Woolly  Apple  Aphis  (Eriosoma  lanigera  Hausm.). — This  European 
pest  has  been  in  the  United  States  for  many  years  and  is  widely  dis- 


200 


APPLIED  ENTOMOLOGY 


tributed.  The  adult  is  a  small  insect  more  or  less  completely  covered  by 
white,  cottony  or  woolly  threads  of  wax  which  practically  conceal  the 
louse  beneath.  Recent  studies  have  shown  that  in  most  cases  at  least, 
the  winter  is  spent  in  the  egg  stage  in  crevices  in  the  bark  of  the  elm. 
The  eggs  hatch  in  spring  and  the  young  lice  pass  to  the  buds  and  attack 
the  leaves  when  these  develop,  causing  them  to  become  deformed,  curled 
and  clustered  together  forming  " rosettes."  Several  generations  partici- 
pate in  this  work. 

During  the  later  spring  months  winged  migrants  are  produced  and 
these  pass  to  the  apple,  hawthorn  and  a  few  other  related  trees  where 

they  locate  on  the  under  side  of  the  leaves 
and  produce  young  which  crawl  to  thin 
places,  wounds  or  water  shoots  and  there 
locate  and  reproduce  during  the  summer  and 
fall  (Fig.  192)  until  cold  weather  comes  on, 
when  migrating  forms  are  produced  which 
return  to  the  elm  where  the  eggs  are  laid. 

This  life  history  is  complicated  by  the 
fact  that  during  the  summer  some  of  the 
plant  lice  migrate  from  the  branches  of  the 
apple  tree  to  its  roots  and  feed  there,  pro- 
ducing knots  and  swellings  which  interfere 
with  the  nutrition  of  the  plant,  and  if  suffi- 
ciently abundant  may  cause  its  death.  These 
lice  are  believed  to  remain  on  the  roots  the 
year  around,  generation  after  generation,  but 
with  their  ranks  recruited  from  time  to  time 
by  migrants  from  the  aerial  members.  Some 
of  the  latter  also,  are  believed  to  remain  on 
the  apple  all  winter  as  hibernating  nymphs. 

The  amount  of  injury  to  the  apple  caused 
by  this  insect  above  ground  is  not  very  great 
except  perhaps  on  nursery  trees.  Woolly  spots 
at  scars  and  wounds  on  the  branches,  notice- 
able chiefly  in  the  fall,  are  not  abundant  enough  to  affect  the  trees 
much,  usually.  The  root  form,  however,  is  sometimes  quite  injurious, 
particularly  south  of  the  latitude  of  Washington,  and  young  orchards 
may  suffer  severely. 

Control. — The  waxy  " woolly"  threads  covering  the  bodies  of  these 
insects  make  control  more  difficult  by  spraying  than  would  otherwise 
be  the  case,  as  the  threads  repel  the  spray.  Nicotine  sulfate  40  per  cent, 
standard  formula,  or  kerosene  emulsion  1  part  to  9  of  water,  driven  with 
much  force  are  about  the  only  treatments  for  the  aerial  forms  which  have 
given  much  success.  It  is  evident  that  elms  growing  near  apple  trees 


FIG.  192. — Apple  twig  show- 
ing Woolly  Apple  Aphis 
(Eriosoma  lanigera  Hausm.) 

and  swellings  of  the  twig  pro- 

duced  by  their  attacks.     About 

twice  natural  size.    (Original.) 


THE  HOMOPTERA 


201 


directly  favor  the  successful  migration  of  this  pest,  and  as  far  as  possible 
therefore,  no  elms  should  be  allowed  to  grow  near  apple  orchards. 

For  the  root  form,  when  sufficiently  injurious  to  make  it  pay,  removing 
the  earth  to  a  depth  of  six  or  eight  inches  over  the  root  area  and  pouring 
kerosene  emulsion  or  nicotine  sulfate  diluted  as  above,  over  this  exposed 
surface,  using  enough  to  thoroughly  wet  the  ground,  has  given  good 
results. 

Nursery  stock  affected  can  be  dipped  in  the  lime-sulfur  wash  or 
in  these  materials,  when  dug  either  for  transplanting  or  sale,  and  as 
the  Northern  Spy  seems  to  be  rather  free  from  this  pest,  using  trees 
grown  on  stocks  of  that  variety  is  desirable. 

The  Grape  Phylloxera  (Phylloxera  vitif olios  Fitch). — This  aphid  is  a  native 
of  America  and  attacks  the  grape.  Native  American  vines,  however,  are  resis- 
tant to  its  work  to  a  considerable  degree,  so  that  injury  to  them  is  not  serious. 


FIG.  193. — Under  surface  of  Grape  leaf  showing  galls  produced  by  the  Grape  Phylloxera 
(Phylloxera  mtifolice  Fitch).  Somewhat  reduced  from  natural  size.  (From  Riley,  U.  5. 
D.  A.) 

The  European  grape  (Vitis  vinifera)  on  the  other  hand,  is  very  susceptible  to 
its  attacks  and  when  the  Phylloxera  reached  Europe  about  1860,  it  became  very 
destructive,  causing  the  loss  of  over  two  million  acres  of  vineyards  before  any 
successful  checks  to  the  insect  were  discovered.  In  this  country  it  reached 
California  where  the  European  grape  is  also  grown,  about  1874  and  has  been  the 
cause  of  great  injury  there  also. 

The  insect  lays  its  eggs,  one  per  female,  on  old  wood  of  the  grape  in  the  fall, 
and  these  eggs  hatch  the  following  spring  into  tiny  lice  which  locate  on  the  upper 
surface  of  the  young  leaves  and  begin  to  suck  the  sap.  This  causes  the  leaf  to 
become  depressed  at  each  place  where  a  louse  is  at  work,  so  that  galls  (Fig.  193) 
projecting  from  the  under  surface  are  soon  produced,  in  which  the  insects  live. 
Upon  becoming  full-grown  these  lice  lay  eggs  in  the  galls  and  the  young  which 
hatch  from  them  pass  to  other  parts  of  the  leaves  and  produce  galls  of  their 


202 


APPLIED  ENTOMOLOGY 


own.     This  process  continues  through  the  summer  but  in  the  fall  the  young 
desert  the  leaves  (Fig.  194)  and  work  down  to  the  roots  and  rest  until  the  follow- 


Fia.  194. —  Grape  Phylloxera:  a,  galls  on  grape  roots;  6,  galls  enlarged,  showing  the 
insects;  c,  Phylloxera  from  a  root  gall:  6  and  c  enlarged.  (From  Sanderson,  Insects  Injuri- 
ous to  Farm,  Garden  and  Orchard;  after  Marlatt,  U.  S.  D.  A.) 


FIG.   195. — Grape  root  showing  galls  caused  by  Phylloxera.      (From  Berlese.) 

ing  spring.  Then  they  attack  the  roots,  forming  swellings  (Fig.  195)  which  on 
young  rootlets  stop  their  growth,  and  on  the  larger  ones  cause  decay  which  spreads 
around  the  root  and  kills  it  beyond  that  point. 


THE  HOMOPTERA  203 

During  the  latter  part  of  this  second  season  some  winged  forms  (Fig.  194) 
are  produced  and  these  make  their  way  up  to  the  surface  of  the  ground  and 
migrate  to  other  vines  where  they  lay  eggs.  These  produce  both  male  and 
female  plant  lice  and  each  female  lays  a  single  fertilized  egg  which  winters  over. 

This  2 -year  life  and  the  production  of  leaf  galls  is  not  always  necessary  to 
the  continued  existence  of  the  insect  however.  The  root  form  generally  goes  on, 
brood  after  brood,  particularly  on  the  European  grape,  without  the  formation 
of  leaf  galls,  and  while  young  from  the  leaves  may  probably  pass  to  the  roots 
at  any  time  during  the  summer,  the  migration  of  root  forms  to  the  leaves  is 
unknown.  Apparently  then,  the  life  history  just  outlined  applies  to  American 
varieties  of  the  vine,  but  in  the  case  of  the  European  species,  while  the  lice  may 
pass  to  the  roots  they  do  not  usually,  at  least,  seem  to  migrate  in  the  reverse 
direction,  the  insects  coming  from  fertilized  eggs  passing  directly  to  the  roots. 
Root  forms  may  spread  to  other  plants  through  the  soil. 

Control. — Four  methods  of  control  have  been  made  use  of  for  this  pest,  viz., 
the  injection  of  Carbon  disulfid  into  the  soil  close  to  the  roots;  flooding  the  vine- 
yard with  water;  planting  in  very  sandy  soils;  and  the  selection  of  resistant 
varieties.  The  first  of  these  has  given  fair  results  where  the  soil  is  loose,  deep  and 
rich,  but  is  most  successful  in  cooler  locations,  and  here  the  insect  is  least  abun- 
dant. It  is  also  rather  expensive  and  has  therefore  largely  been  replaced  by  other 
treatments. 

Submersion  of  the  ground  under  water  is  a  better  method,  but  obviously 
cannot  be  made  use  of  in  most  cases.  The  vineyard  must  be  kept  covered  with 
at  least  six  inches  of  water  in  order  to  drown  the  lice  and  unfortunately  the  best 
time  to  do  this  is  during  the  summer  when  the  vines  are  most  liable  to  be  injured 
by  this  treatment.  The  time  chosen  therefore,  is  after  the  vines  have  stopped 
active  growth  but  before  the  lice  have  become  dormant.  In  California  this  is 
generally  some  time  in  October.  Flooding  then  should  last  from  a  week  to 
10  days:  later  in  the  season  it  must  be  extended  and  in  the  winter  months  35 
to  40  days  of  treatment  is  necessary. 

Planting  in  sandy  soil  is,  for  some  reason  not  understood,  a  protection  of  the 
vines  against  Phylloxera,  particularly  where  it  contains  a  high  percentage  of 
siliceous  sand.  It  is  not  always  possible  to  locate  vineyards  on  such  soil  however. 

The  selection  of  resistant  varieties  of  the  grape  is  now  the  favored  method  of 
control.  With  such  varieties  the  insects  when  present  on  the  roots  do  not  in- 
crease rapidly  and  the  diseased  tissue  of  the  swellings  on  the  roots  does  not  go 
deeper  than  the  bark,  leaving  the  roots  proper  quite  healthy.  At  the  present 
time  the  grafting  of  vinifera  varieties  on  resistant  stalks  which  preserves  the 
resistant  properties  of  the  roots  while  producing  the  vinifera  quality  of  grapes 
so  much  desired,  seems  to  give  the  best  results  in  vineyards,  though  the  proper 
combination  of  different  varieties  of  the  two  calls  for  a  detailed  knowledge  of 
the  subject  in  actual  practice. 

The  Corn  Root  Aphis  (Aphis  maidi-radicis  Forbes). — This  insect,  though  it 
can  hardly  be  regarded  as  universally  distributed  through  the  United  States, 
is  both  a  serious  pest  of  corn  over  a  large  area  and  because  of  its  interesting  rela- 
tion with  ants,  an  interesting  species.  It  appears  to  occur  throughout  the 
eastern  United  States  as  far  west  as  South  Dakota  and  Colorado  and  south  to 
South  Carolina,  Louisiana  and  Texas,  but  its  destructive  work  mainly  covers  the 
territory  from  New  Jersey  to  South  Carolina  and  west  to  the  Mississippi  River. 


204 


APPLIED  ENTOMOLOGY 


The  eggs  of  this  aphid  hatch  early  in  spring  and  from  10  to  22  generations 
(Figs.  196  and  197)  are  produced  during  the  season.  As  cool  fall  weather 
appears,  a  generation  of  sexual  individuals  (Fig.  198)  appears  and  these  lay 
eggs  which  pass  the  winter.  During  this  season  they  may  be  found  in  the 
ground  in  nests  of  several  kinds  of  ants  but  most 
frequently  in  those  of  the  little  brown  ant,  Lasius  niger 
americanus.  They  are  oval,  black  and  glistening  and 
are  sometimes  found  in  small  piles  in  the  nests  of  the 
ants.  In  cold  weather  the  ants  carry  the  eggs  down 
below  the  frost  and  on  warm  days  bring  them  up  to 
warmer  levels.  In  spring,  when  various  weeds  such  as 
smartweed,  begin  to  grow,  the  ants  tunnel  along  the 
roots  of  these  weeds  and  place  the  young  lice  as  they 
hatch,  on  them  to  feed.  Later,  when  corn  roots 
become  available  the  ants  transfer  the  lice  to  them, 
where  they  and  their  descendants  feed  during  the  rest 
of  the  season.  Winged  migrants  are  produced  after  a 
generation  or  two  and  these  individuals  spreading,  are 
taken  to  corn  roots  by  ants  which  may  find  them.  All 
summer  and  fall  the  ants  care  for  the  lice,  taking  them 
from  one  plant  to  another  and  collecting  from  them  the 
honey-dew  upon  which  the  ants  feed.  In  the  fall  when 
the  eggs  are  laid  these  are  gathered  by  the  ants  and 
stored  in  their  nests  over  winter. 

Where  the  Corn  Root  Aphid  is  abundant  it  becomes  a  serious  corn  pest, 
dwarfing  the  corn  and  turning  the  leaves  yellow  or  reddish  and  sometimes  destroy- 
ing the  plants,  particularly  when  weather  conditions  are  also  unfavorable. 


FIG.  196. — Corn  Root 
Aphis  (Aphis  maidi- 
radicis  Forbes) ;  wingless, 
viviparous  female. 
Greatly  enlarged.  (From 
U.  S.  D.  A.  Bur.  Ent. 
Bull.  85,  Part  VI.) 


FIG.   197. — Winged,  vivipa'rous  female  of  the  Corn  Root  Aphis,  greatly  enlarged. 
U.  S.  D.  A.  Bur.  Ent.  Butt.  85,  Part  VI.) 


(From 


Control. — Rotation  of  crops  is  of  much  value  as  a  control,  for  as  the  lice 
cannot  migrate  until  their  second  generation,  corn  planted  on  land  where  they 
are  not  already  present  will  get  well  started,  Fertilization  and  frequent  cultiva- 


THE  HOMOPTERA 


205 


tion  to  produce  vigorous  growth  will  aid  in  this.  The  worst  injuries  are  usually 
where  corn  is  planted  to  follow  corn  and  therefore  where  this  pest  is  already 
present  in  the  field  from  the  preceding  year.  Any  method  which  will  destroy 
the  nests  of  the  ants  which  care  for  the  lice  will  also  be  helpful,  and  deep  plowing 
and  harrowing  both  in  late  fall  and  early  spring  has 
proved  of  value  for  this  purpose. 

Some  plant  lice  attack  evergreens  and  pro- 
duce rather  soft,  fleshy  galls,  generally  at  the 
bases  of  the  outer  shoots.  These  appear  during 
the  spring  months  and  are  of  full  size  by  mid- 
summer. They  then  dry  and  crack  open,  showing 
little  cavities  occupied  by  the  plant  lice  which  now 
leave  the  galls  for  other  parts,  either  of  the  same  or 
some  other  kind  of  tree,  according  to  the  species 
concerned.  The  gall  formation  interferes  with  the 
growth  of  the  tree  by  preventing  wholly  or  in 
part,  the  circulation  of  the  sap  in  the  shoot  at  the 
base  of  which  the  gall  is  located,  and  this  results, 

by  the  death  or  checking  of  the  growth,  in  trees  which  look  thin  rather 
than  dense,  and  in  some  cases  they  may  become  worthless  as  lawn 
ornaments.  In  the  East  the  spruce  is  often  seriously  injured  in  this  way. 

Many  kinds  of  plant  lice  often  become  seriously  abundant  for  periods 
of  2  or  3  years,  then  disappear  for  a  time.  The  Potato  Plant  louse,  the 
Pea  louse,  the  Beet-root  louse,  Cherry  plant  lice  and  others  have  all  been 
destructive  for  a  year  or  two  at  a  time  within  the  last  decade,  and  similar 
outbreaks  of  these  or  others  may  be  expected  any  year.  Wherever  it  is 
possible,  spraying  thoroughly  upon  the  first  appearance  of  the  lice,  with 


FIG.  198. — Oviparous 
female  of  the  Corn  Root 
Aphis,  greatly  enlarged. 
(From  U.  S.  D.  A.  Bur. 
Ent.  Bull.  85,  Part  VI.) 


FIG.  199. — Aphid  parasite   (Lysiphlebus  testaceipes  Cress.)   ovipositing  in  the  body  of  a 
Spring  Grain  Aphis.     Greatly  enlarged.      (From  U.  S.  D.  A.  Bur.  Ent.  Bull.  110.) 

nicotine  sulfate,  kerosene  emulsion  or  fish-oil  soap  should  be  resorted  to 
as  measures  of  relief.  If  for  any  reason  this  cannot  be  done  and  no  special 
method  of  control  seems  available,  dependence  must  be  placed  upon 
climatic  influences  and  insect  enemies  to  check  these  pests,  and  this  will 
occur  within  2  or  3  years  in  nearly  every  case. 

Among  their  many  enemies  is  one  group  of  tiny  insects  which  makes  a 
specialty  of  attacking  plant  lice.     An  insect  of  this  group  will  select  a 


206 


APPLIED  ENTOMOLOGY 


louse  (Fig.  199)  and,  facing  it,  will  thrust  its  abdomen  forward  beneath 
its  body  and  drive  its  ovipositor  into  the  louse.  The  young  parasite 
hatching  from  an  egg  thus  deposited,  will  feed  upon 
the  aphid  whose  body  becomes  distended  and 
generally  changes  color  after  a  time  and  finally 
dies  adhering  to  the  plant  on  which  it  was.  When 
the  parasite  has  completed  its  development  within 
the  body  of  the  louse  it  escapes  by  cutting  a 
circular,  lid-like  opening  through  the  skin  (Fig.  200), 
and  lice  attacked  and  killed  in  this  way  are  often 
very  plentiful  during  and  particularly  toward  the 
end  of  a  period  of  destructive  abundance  of  these 
insects  (see  page  344). 

Family  Aleyrodidae. — The  adults  of  the  insects 
belonging  in  this  family  (Fig.  201)  are  very  small 
and  have  four  wings  which  are  broadly  rounded 
and  have  a  white  dust  covering  them,  which  has 
led  to  calling  the  group  the  White  Flies.  Occa- 
sionally the  wings  have  dark  spots  or  streaks.  The 
eyes  are  often  constricted  in  the  middle  or  even 
divided  into  two  parts.  The  body  is  generally 
yellowish,  though  in  some  species  it  may  be  of 
other  colors. 

The  nymph  on  hatching,  crawls  around  for  a 
short  time  before  settling  down  on  a  leaf,  then  in- 
serts its  rostrum  in  the  tissues  and  begins  to  feed. 

After  molting  the  insect  becomes  quiet,  with  its  legs  and  antennae  much 
reduced,  and  thereafter  does  not  move  from  its  location  until  it  becomes 


FIG.  200.— Plant  Lice 
killed  by  parasites.  Up- 
per figure  shows  the 
circular  piece  of  chitin 
cut  by  the  parasite  in 
escaping,  but  still  at- 
tached. Lower  figure 
shows  the  parasite  just 
escaping.  Much  en- 
larged. (From  U.  S.  D. 
A.  Bur.  Ent.  Bull.  110.) 


FIG.  201. — Adult  White  Flies  twice  natural  size.      (From  Britton,  Second  Report  Ent.  Conn. 

Agr.  Exp.  Sta.  1902.) 

adult,  and  wax  which  may  have  been  produced  before  the  first  molt, 
now  becomes  more  noticeable.     This  wax  may  take  the  form  of  a  fringe 


THE  IIOMOPTERA  207 

around  the  sides  and  may  more  or  less  cover  the  body.  The  animal  after 
its  third  molt  differs  so  from  its  former  appearance  that  this  stage  is 
often  called  a  pupa,  and  as  the  following  molt  produces  the  adult  there 
is  evidently  quite  a  metamorphosis  to  justify  the  use  of  this  term  in  the 
group.  Honey-dew  is  produced  by  these  insects. 

White  Flies  are  essentially  tropical  though  a  few  species  live  in  the 
northern  United  States.  In  greenhouses  everywhere  the  Greenhouse 
White  Fly  (Aleyrodes  vaporariorum  Westw.)  is  too  often  a  serious  pest, 
for  it  multiplies  rapidly  and  the  tiny  nymphs  (Fig.  202)  are  not  generally 
noticed  in  time  to  check  their  increase  before  the  plants  have  suffered 


FIG.  202. — Nymphs  of  the  White  Fly  on  underside  of  a  leaf,  enlarged  twice.     (From 
Britton,  Second  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1902.) 

greatly.  When  they  are  abundant,  fumigation  for  3  hr.  at  night,  using 
between  J£  and  J£  oz.  of  sodium  cyanid  to  each  1,000  cu.  ft.  of  space  in 
the  greenhouse  should  kill  all  but  the  eggs  and  some  of  the  pupae,  and 
repeating  this  treatment  twice  afterwards  at  intervals  of  2  weeks  should 
destroy  the  others  in  the  stages  to  which  they  will  have  then  progressed. 
If  for  any  reason  this  treatment  is  not  desirable,  syringing  the  plants 
with  fish-oil  soap  using  from  1  to  Ij-^  oz.  per  gallon  of  water,  giving 
particular  attention  to  the  under  surface  of  the  leaves  will  give  some  relief. 

In  the  Southern  States  and  in  California,  white  flies  attack  citrus  fruits  and 
cause  much  injury.  Several  species  are  more  or  less  concerned,  the  most  impor- 
tant one  being  the  Citrus  White  Fly  (Dialeurodes  citri  Ashm.).  These  insects 
usually  check  the  growth  of  the  tree  and  fruit,  reducing  the  yield  and  its  size, 
and  also  by  the  production  of  honey-dew,  induce  the  growth  in  this  of  a  fungus 
called  "sqoty  mould"  which  interferes  with  the  ripening  of  the  fruit  and  is  also 
believed  to  affect  its  flavor,  besides  making  it  look  objectionable,  so  that  fruit 
partly  covered  with  the  mould  must  be  cleaned  before  shipping.  The  reduction 
of  the  vitality  of  the  tree  by  these  insects  also  favors  the  more  active  development 
of  other  citrus  insects  and  of  diseases. 


208  APPLIED  ENTOMOLOGY 

Certain  fungi  live  on  the  white  flies,  however,  and  are  of  assistance  in  their 
control,  but  as  they  need  certain  weather  conditions  for  their  best  growth  during 
about  3  months,  they  can  rarely  accomplish  more  than  a  third  of  the  amount 
of  control  necessary. 

Spraying  with  paraffin-oil  emulsion  prepared  according  to  special  directions 
has  proved  to  be  a  successful  method  of  control  for  citrus  white  flies,  and  miscible 
oil  has  also  given  good  results.  In  either  case  the  material  as  applied  should 
contain  about  1  per  cent  of  oil. 

Family  Coccidae  (Scale  Insects). — These  are  remarkable  insects 
having  been  much  modified  and  changed  in  appearance  from  the  more 
ordinary  forms.  Without  attempting  an  accurate  classification,  they 
may  be  grouped  under  three  heads:  the  armored  scales,  the  soft  scales, 
and  the  mealy  bugs. 

The  mealy  bugs  are  the  least  degenerate  of  the  three  groups.  In 
them  the  females  preserve  their  body  segments,  eyes,  antenna?  and  legs, 
and  can  move  about.  They  secrete  a  waxy  material,  usually  as  long 
cottony  threads  or  plates,  more  or  less  covering  their  bodies  and  some- 
times forming  a  large  egg  sac  at  the  hinder  end.  In  the  female  soft 
scales  the  antennaB  and  legs  are  not  lost  but  they  become  reduced  to 
such  an  extent  that  though  the  adult  can  move  about  somewhat,  it 
seldom  does  so.  Wax  when  secreted,  is  usually  to  form  a  sac  at  the  hinder 
end  of  the  body  enclosing  the  eggs,  and  the  skeleton  on  the  back  of  the 
insect  becomes  very  much  thickened,  forming  a  scale,  often  very  convex, 
strong  and  protective,  though  seemingly  softer  than  in  the  armored 
scales.  In  this  last-named  group  the  female  loses  antennae,  eyes,  and 
legs,  and  secretes  a  waxy  scale,  with  which  the  molted  skins  from  the 
body  are  felted  together,  forming  generally  a  rather  flat  and  very  tough 
scale.  The  metamorphosis  in  the  females  of  all  three  groups  is  incom- 
plete. In  some  cases  the  females  are  fertilized  before  they  have  attained 
full  size  and  grow  considerably  afterwards. 

The  males  develop  much  as  do  the  females,  at  first,  though  not  losing 
any  of  their  parts  by  degeneration.  After  reaching  full  size,  however, 
they  pupate  and  emerge  from  the  pupa  as  very  tiny  insects  with  only  one 
pair  of  wings  and  no  mouth  parts.  Thus  in  the  scale  insects  we  have  the 
remarkable  fact  that  while  in  the  males  there  is  a  complete  metamorpho- 
sis, in  the  females  it  is  incomplete.  Whether  the  former  was  the  original 
condition  in  the  group,  and  the  females  through  the  degeneration  con- 
nected with  their  mode  of  life  have  changed  to  an  incomplete  meta- 
morphosis, or  whether  this  was  the  primitive  condition  and  complete 
metamorphosis  has  been  developed  in  the  males,  is  unknown,  though  the 
other  Homoptera  all  have  an  incomplete  metamorphosis. 

About  2,000  species  of  scale  insects  are  known,  attacking  nearly  all 
kinds  of  trees  and  shrubs,  and  sometimes  other  plants  as  well.  Many 
have  an  almost  incredible  rapidity  of  increase,  and  when  under  favorable 


THE  HOMOPTERA  209 

conditions,  this  results  in  the  death  of  the  plant  they  are  on.  A  few  are 
beneficial  to  man.  Thus  the  bodies  of  a  scale  feeding  upon  cactus,  when 
dried  and  prepared,  furnish  the  dye  known  as  Cochineal.  Shellac  is 
obtained  from  the  excretions  produced  by  another  scale,  and  China  wax, 
used  as  furniture  polish,  comes  from  a  third  species.  Most  scale  insects, 
however,  are  injurious  and  fail  to  compensate  for  the  injury  they  cause  by 
producing  anything  of  value. 

Among  so  many  serious  pests,  only  a  few  can  be  considered  in  detail 
here.  Taking  the  armored  scales  first,  these  are  the  Oyster  shell,  the 
Scurfy  and  the  San  Jose  Scales,  with  brief  reference  to  a  few  others. 

Armored  Scales 

The  Oyster-shell  Scale  (Lepidosaphes  ulmi  L.). — This  insect,  native 
to  Europe,  has  been  so  long  in  this  country  that  it  is  now  very  generally 
distributed.  It  is  chiefly  an  enemy  of  the  apple,  pear,  poplar,  willow, 
ash  and  lilac,  but  is  often  found  on  other  plants.  It  feeds  on  all  parts 
covered  by  bark,  and  the  male  scales  are  also  often  found  on  the  leaves. 


FIG.  203. — Female  scales  of  the  Oyster-shell  Scale  (Lepidosaphes  ulmi  L.)  on  a  twig,  about 
twice  natural  size.     (Original.) 

The  full-grown  female  scale  (Fig.  203)  is  about  one-eighth  of  an  inch 
long  and  has  much  the  form  of  an  oyster  shell,  one  end  narrowly  rounded, 
the  other  rather  more  broadly  so,  and  the  shell  as  a  whole  usually  bent 
somewhat  to  one  side.  It  is  brown  to  gray  in  color,  varying  with  age, 
and  to  some  extent,  the  plant  it  is  on.  During  the  winter  examination 
of  the  scale  will  show  beneath  it  at  the  narrower  end,  the  dead  body  of  the 
insect,  and  behind  it  from  15  to  100  tiny  whitish  eggs.  These  hatch  the 
following  May  or  June,  according  to  the  advancement  of  the  season,  into 
very  small  whitish  nymphs  or  ''crawling  young,"  which  are  extremely 
delicate  and  with  no  scale.  These  young  crawl  out  from  beneath  the 
parent  scale  and  wander  about  for  a  few  hours  or  even  a  day  or  so,  seeking 
for  places  where  they  may  settle:  then  each  thrusts  its  beak  through 
the  bark  and  begins  feeding,  and  degeneration  of  eyes,  antennae  and 
limbs,  and  the  secretion  of  wax  over  the  body  begins.  To  this  secretion 
the  molted  skin  is  added  at  each  molt,  making  a  very  tough,  hard,  cover- 

14 


210  APPLIED  ENTOMOLOGY 

ing  scale.  The  insect  beneath  this  becomes  adult  after  a  time  and 
following  the  laying  of  its  eggs,  dies.  In  the  northern  states  the  eggs  are 
laid  in  August  or  September,  but  in  the  middle  states  and  farther  south, 
the  earlier  seasons  permit  hatching  enough  earlier  in  the  season  for  the 
adult  condition  to  be  reached  and  the  eggs  laid  by  midsummer,  and  these 
eggs  soon  hatch  and  produce  egg-laying  adults  before  the  following 
winter.  Thus,  this  insect  though  having  but  one  generation  each  year 
in  the  more  northern  states,  has  two  from  about  the  latitude  of  New 
Jersey  southward,  except  at  such  altitudes  as  to  produce  northern 
conditions. 

Many  of  the  male  crawling  young  go  to  the  leaves  to  settle  and  the 
scales  they  form  are  smaller  and  somewhat  different  in  shape  from  those 
of  the  females.  Beneath  them  they  attain  their  growth,  then  pupate, 
still  under  their  scales,  and  at  the  end  of  this  process  emerge  as  very 
small  two-winged  adults  without  any  mouths  or  mouth  parts,  having  un- 
dergone a  complete  metamorphosis. 

Control. — These  insects  are  least  protected  while  crawling  young,  and 
as  they  are  sucking  forms,  a  contact  insecticide  should  be  applied 
while  they  are  moving  about  or  at  least  before  they  have  had  time  to 
produce  scales  covering  themselves.  The  usual  treatment  therefore  is 
to  spray  with  1  part  of  kerosene  emulsion  to  9  of  water,  or  with  Nicotine 
sulfate  40  per  cent,  1  part,  water  800  to  1,000  parts,  as  soon  as  the  young 
appear.  They  are  so  small,  however,  that  it  is  very  difficult  to  reach 
them  all  with  the  spray,  and  as  all  do  not  hatch  at  the  same  time,  a 
second  application  about  10  days  after  the  first,  is  desirable.  Winter 
spraying  with  lime-sulfur  wash  is  also  a  fairly  good  treatment.  Where 
neither  of  these  methods  proves  effective  (as  is  sometimes  the  case), 
spraying  in  spring,  shortly  before  the  eggs  hatch,  with  linseed  oil  emulsion, 
has  worked  well.  This  is  prepared  as  follows: 

Raw  linseed  oil 1       gal. 

Hard  soap : }/2      Ib. 

Water,  to  make 10      gal. 

Dissolve  the  soap  in  the  water;  add  the  oil  and  churn  through  a 
pump  as  for  kerosene  emulsion  until  thoroughly  mixed  (it  does  not 
thicken  up  like  the  latter)  and  spray. 

The  Scurfy  Scale  (Chionaspis  furfura  Fitch). — This  insect  is  a  native 
of  America  and  is  usually  less  abundant  in  the  more  northern  states  than 
elsewhere,  attacking  the  apple,  pear,  mountain  asn,  currant,  gooseberry, 
hawthorn,  Japanese  quince  and  other  plants.  The  full-grown  female 
scale  (Fig.  204)  is  shorter  and  broader  than  the  Oyster-shell  scale, 
and  when  perfect  in  outline,  rather  pear-shaped,  and  dirty  white  in  color. 
Its  life  and  habits  are  much  the  same  as  those  of  the  Oyster-shell  scale, 


THE  HOMOPTERA 


211 


but  the  eggs  are  fewer  in  number  and  dark  purple  in  color,  as  are  also  the 
crawling  young  which  usually  hatch  a  few  days  later  in  the  season  than 
the  other  species.  Control  methods  are  the  same  as  for  the  Oyster-shell 
scale. 


FIG.  204. — Scurfy  Scales  (Chionaspis  furfura  Fitch).  Male  scales  at  right,  female 
scales  at  left.  Left  hand  figure  greatly  enlarged ;  the  other  two  somewhat  enlarged.  (From 
U.  S.  D.  A.  Farm.' Bull.  723.) 


The  San  Jose  Scale  (Aspidiotus  perniciosus  Comst.). — This  is  one  of 
the  most  serious  pests  among  the  scale  insects.  Its  original  home  was 
probably  China,  but  it  appears  to  have  reached  California  about  1870 
and  since  then  has  spread  practically  all  over  this  country.  It  has  a 
wide  range  of  food  plants,  on  many  of  which  it  thrives  sufficiently  to 
quickly  kill  them.  The  plants  which  suffer  most  from  its  attacks  are 
the  fruit  trees  and  currants,  the  dog-woods,  thorns,  poplars,  ornamental 
cherries  and  plums,  hardy  roses,  willows,  lilacs  and  lindens;  and  even 
maples  and  elms  are  sometimes  attacked,  the  total  list  of  plants  upon 
which  it  has  been  found  numbering  over  a  hundred.  It  feeds  on  all 
parts  of  the  plant  above  ground,  even  including  the  fruit. 

The  full-grown  female  scale  (Fig.  205)  is  about  the  size  of  a  pin  head, 
nearly  circular  in  outline  and  rather  flat,  sloping  gradually  upward  from 


212 


APPLIED  ENTOMOLOGY 


its  edge  to  near  the  center  where  a  slight  circular  depression  surrounds 
the  raised  center  or  " nipple"  itself.  It  is  brownish-gray  in  color  when 
adult,  but  in  earlier  stages  may  vary  from  this.  The  adult  male  scale 
is  somewhat  smaller,  more  oval  in  outline,  and  with  the  nipple  not  cen- 
trally placed  but  nearer  one  end. 

At  the  beginning  of  the  winter  season  specimens  of  this  scale  of 
practically  all  ages  occur,  but  probably  only  those  from  about  one-third 
to  one-half  or  two-thirds  grown  survive  the  winter.  In  the  spring  these 

individuals  resume  their  feeding  on 
the  sap  and  after  a  time  the  males 
appear.  In  the  northern  states 
this  condition  is  hardly  reached 
before  the  middle  of  May,  but  at 
Washington,  D.  C.  it  comes  early 
in  April,  and  farther  south  still 
earlier.  After  mating,  the  females 
continue  to  grow  and  about  a 
month  later  the  first  young  appear. 
These  do  not,  in  the  San  Jose 
Scale,  hatch  from  eggs  laid  by  the 
parent  but  the  young  are  born 
alive;  i.e.,  this  insect  is  viviparous. 
These  young  are  produced,  a  few 
every  day  or  two,  and  the  parent 
lives  for  a  month  or  more,  pro- 
ducing an  average  total  of  about 
FIG.  205.— San  Jose  Scale  (Aspidiotus  400  young.  These  resemble  the 
pernidosus  Comst.) :  adult  female  scales  crawling  young  of  the  scales  already 

enlarged   about  five   times.      (From   Houser,  •  i          i 

Ohio  Agr.  Exp.  Sta.  Bull.  332.)  considered,   except    that   they   are 

lemon  yellow    in    color,   and  they 

crawl  about  and  settle  down  to  feed  in  the  same  way.  The  scale 
now  begins  to  appear,  at  first  as  white  waxy  threads  over  the  back, 
which  soon  mat  together  to  form  a  pure  white  covering.  As  the 
nymph  beneath  molts,  the  molted  skins  are  added  to  this  and  variations 
in  color  of  the  scale  appear.  Sometimes  the  scale  of  the  partly  grown 
insect  may  show  white,  black  and  gray,  varying  in  arrangement  according 
to  the  completeness  with  which  the  different  parts  have  combined,  but 
before  maturity  it  becomes  a  quite  uniform  grayish-brown.  The  young 
become  adult  in  a  little  over  a  month  and  then  themselves  begin  to 
produce  young,  and  in  the  northern  states  there  are  usually  at  least 
three  generations  in  a  season,  while  in  the  south  there  are  four  or  even 
more.  The  generations  overlap,  the  earliest  young  produced  by  the 
second  generation  for  example,  sometimes  appearing  before  the  last  born 
of  the  preceding  one,  which  results  in  the  almost  constant  presence  of 


THE  HOMOPTERA  213 

crawling  young  on  an  infested  tree,  from  the  time  the  first  one  appears 
until  reproduction  is  stopped  by  cold  weather.  Assuming  the  production 
of  four  full  generations  in  a  season,  equally  divided  between  the  sexes, 
and  with  no  loss  in  number  from  death  by  accident  or  other  causes  to 
reduce  the  number  produced,  we  have  a  total  of  3,216,080,400  in  individ- 
uals as  the  descendants  during  one  season  from  a  single  pair.  Fortu- 
nately, many  never  reach  maturity,  or  an  infested  tree  would  often 
be  sucked  dry  before  winter. 

The  San  Jose*  Scale  has  a  number  of  parasites  which  are  sometimes 
quite  effective,  destroying  a  large  per  cent  of  the  scales  in  some  localities, 
but  with  such  an  enormous  power  of  increase  of  the  pest,  even  a  high 
degree  of  parasitism  fails  to  give  the  relief  needed.  A  few  predaceous 
insects  are  also  known,  which  feed  upon  the 
scale.  Most  noticeable  among  these  is  the 
Twice-stabbed  Lady  Beetle  (Chilocorus  bivulnerus 
Muls.),  a  small  black  beetle  (Fig.  206)  with  two 
red  spots.  It  is  nearly  circular  in  outline,  very 
convex  and  is  about  one-eighth  of  an  inch  long. 
A  fungous  disease  also  attacks  the  scale,  par- 
ticularly in  the  South,  but  parasites,  predaceous  FlG  a206._Twice.stabbed 
foes  and  diseases  together,  generally  fail  to  hold  Lady  Beetle  (Chilocorus  bi- 

it  entirely  in  check.  vulnerus  Muls.) :  a,  adult;  b 

^  .,.__.  larva   enlarged:  real   length 

A  lady  beetle  closely  resembling  the  Twice-  shown  by  the  hair  lines, 
stabbed  Lady  Beetle  is  an  enemy  of  the  scale  in  W™™  Sanderson  and 

Jackson,    Elementary    Ento- 

China,  the  native  home  of  the  pest,  and  this    moiogy.  after  RUey.) 
insect  has  been  brought  to  the  United  States 

with  the  hope  that  it  might  do  effective  work  here,  but  thus  far,  for 
various  reasons,  it  has  failed  to  accomplish  much. 

Control. — Spraying  as  for  the  Oyster-shell  Scale  is  useless,  for  that 
treatment  is  based  upon  the  destruction  of  the  delicate,  crawling  young, 
by  one  or  at  most  two  applications.  With  the  San  Jose*  Scale,  however, 
the  young  do  not  all  appear  at  about  the  same  time,  but  are  present 
practically  from  May  or  June  according  to  the  latitude  of  the  locality, 
until  winter.  To  use  this  method  successfully  therefore  would  require 
spraying  about  every  2  weeks  or  so  for  a  period  of  at  least  5  months — 
a  treatment  manifestly  impracticable. 

Stronger  materials  are  therefore  used,  during  the  dormant  season, 
when  the  tree  is  least  liable  to  injury  by  the  spray,  and  when  a  more 
thorough  application  can  be  made,  the  leaves  having  fallen.  For  this 
purpose  the  lime-sulfur  wash  and  miscible  oils  are  generally  used  (see 
Chapter  VIII).  At  times  injury  to  the  trees  has  been  observed  following 
the  use  of  miscible  oils,  but  on  the  other  hand  these  materials  spread 
better  over  the  tree  than  the  lime-sulfur.  Many  persons  now  make  a 
practice  of  spraying  every  third  winter  with  miscible  oil,  but  using  the 
lime-sulfur  at  other  times. 


214 


APPLIED  ENTOMOLOGY 


In  some  cases  summer  treatment  may  be  desirable  where  the  scale 
is  increasing  rapidly,  to  preserve  the  tree  until  winter  gives  an  oppor- 
tunity for  the  regular  application.  In  such  cases  a  greater  dilution  of  the 
lime-sulfur  becomes  necessary,  and  with  stone-fruit  trees  the  self-boiled 
material  should  be  used. 

Fumigation  with  Hydrocyanic  acid  gas  is  the  most  effective  treatment 
for  the  San  Jose  Scale,  but  the  cost  of  the  tents  large  enough  to  cover  all 
but  the  smallest  trees  is  so  great  that  this  method  is  made  use  of  only  for 
fumigating  nursery  stock  after  it  has  been  dug,  in  houses  built  for  that 
purpose. 


a  b 

FIG.    207. —  Rose    Scales   (Aulacaspis  rosce  Bouche):    a,     female    scales;  6,   male    scales. 
Considerably  enlarged.     (From  Houser,  Ohio  Agr.  Exp.  Sta.  Bull.  332.) 

The  Rose  Scale  (Aulacaspis  rosce  Bouche). — Generally  distributed  in  the 
United  St.ates  on  raspberry,  blackberry,  dewberry,  rose,  pear  and  some  other 
plants.  Female  scales  (Fig.  207)  white  with  more  or  less  yellow  at  margin; 
nearly  circular,  about  one-tenth  of  an  inch  in  diameter.  Male  scales  white,  nar- 
row, very  small  Plants  thickly  infested  appear  as  though  sprayed  with  white- 


THE  HOMOPTERA 


215 


wash.  Winters  in  various  stages,  so  all  may  be  present  at  almost  any  time. 
Two  or  three  generations  per  year.  Control  by  cutting  out  the  worst  infested 
stems  during  the  winter,  and  spraying  with  lime-sulfur  as  for  San  Jose"  Scale  in 
early  spring.  Whale-oil  soap  (1  Ib.  in  1  gal.  water)  may  also  be  used. 

The  Pine-leaf  Scale  (Chionaspis  pinifolice  Fitch). — Occurs  generally  in  the 
United  States  on  leaves  of  pine,  and  sometimes  other  evergreens.  Female  scale 
(Fig.  208)  white,  narrower  than  Scurfy  Scale  but  varying  to  fit  the  width  of  the 
leaf:  male  scale  much  smaller.  When  abundant,  whole  branches  may  appear 


FIG.  208. — Pine-leaf  Scale  (Chionaspis  pinifolice  Fitch).     Female  scales  on  pine  leaf,  about 
twice  natural  size.      (Original.) 


as  though  their  leaves  had  been  sprayed  with  whitewash.  Two  generations  a 
year,  purplish  crawling  young  appearing  in  the  northern  states  about  the  middle 
of  May  and  the  first  of  September,  at  which  times  spray  with  either  kerosene 
emulsion  or  the  linseed  oil  emulsion  as  advised  for  the  Oyster-shell  Scale. 

The  Purple  Scale  (Lepidosaphes  beckii  Newm.). — In  the  South  and  on  the 
Pacific  Coast  this  insect  is  very  injurious  to  citrus  plants,  even  on  the  fruit  of 
which  it  is  often  seen.  It  greatly 
resembles  the  Oyster-shell  Scale  in 
appearance  (Fig.  209)  and  size  There 
are  three  or  four  generations  each 
year.  Control  is  usually  by  fumiga- 
tion with  Hydrocyanic  acid  gas  during 
the  colder  months. 


FIG.  209.  FIG.  210. 

FIG.  209. — Purple  Scale  (Lepidosaphes  beckii  Newm.),  about  natural  size.  (Modified 
from  Cal.  Agr.  Exp.  Sta.  Bull.  226.) 

FIG.  210. — Red  Scale  (Chrysomphalus  aurantii  Mask.)  on  a  portion  of  a  grape  fruit. 
About  natural  size.  (From  Cal.  Agr.  Exp.  Sta.  Bull.  214.) 

The  Red  Scale  (Chrysomphalus  aurantii  Mask.). — A  serious  pest  of  citrus 
trees  in  California.  The  female  scale  resembles  the  San  Jose*  Scale  in  outline, 
but  averages  larger  (Fig.  210)  and  the  scale  is  transparent  enough  to  allow  the 
red  body  (yellow  in  a  variety)  of  the  insect  to  show  through.  The  male  scales 
are  smaller  and  rather  elongate.  The  life  history  is  similar  to  that  of  the  San 


216 


APPLIED  ENTOMOLOGY 


Jose  Scale,  the  young  being  born  alive  during  the  summer  months.  Control  on 
citrus  trees  appears  to  be  best  obtained  by  fumigation  with  Hydrocyanic  acid  gas, 
but  with  deciduous  fruit  trees  the  lime-sulfur  wash  may  be  used. 

Occasionally  the  lenticels  or  breathing  pores  through  the  bark  of 
plant  twigs  resemble  armored  scales,  particularly  the  more  circular 
ones.  To  determine  in  any  case  whether  a  debatable  structure  on  bark 
is  a  scale  or  only  a  lenticel,  it  may  be  scraped  with  the  finger  nail.  If  it 
can  be  removed  without  breaking  the  bark  (it  may  leave  a  whitish  mark) 

the  object  is  a  scale,  but  if  the  bark  is  neces- 
sarily torn  or  broken  to  get  it  off,  it  may  be 
assumed  that  it  was  a  lenticel. 

Soft  Scales 

As  a  group  the  soft  scales  are  less  injurious 
than  the  armored  scales.  Their  rate  of  in- 
crease is  less,  their  covering  less  protective, 
and  their  larger  size  renders  them  more  cer- 


FIG.  211.  FIG.  212. 

FIG.  211. — Tulip  Tree  Scale  (Eulecanium  tulipiferce]  Cook),  about  natural  size. 
(Original.} 

FIG.  212. — Black  Scale  (Saisettia  oleoe  Bern.),  about  natural  size.  (From  Cal.  Agr. 
Exp.  Sta.  Bull.  223.) 

tain  to  be  reached  by  sprays.  The  largest  one  found  in  the  United  States 
is  the  Tulip  Tree  Scale,  the  adult  female  scale  being  about  one-third  of  an 
inch  in  diameter  (Fig.  211).  An  African  soft  scale  is  known  which  is 
about  an  inch  long. 

The  Black  Scale  (Saissetia  oleoe  Bern.). — This  scale  is  found  in  nearly  all 
parts  of  the  world.  It  has  a  long  list  of  food  plants  but  is  chiefly  a  pest  on  citrus 
trees  and  the  olive,  oleander,  apricot  and  prune.  In  the  United  States  it  is 
therefore  chiefly  important  in  the  South  and  West.  The  adult  female  scale  is 


THE  HOMOPTERA 


217 


from  one-eighth  to  one-fourth  of  an  inch  in  diameter  and  almost  hemispherical  in 
form,  black  in  color  and  with  ridges  forming  an  "H"  on  the  back  (Fig.  212). 
The  male  scales  are  much  smaller,  long,  narrow  and  flat.  The  eggs,  from  50  to 
3,000,  are  for  the  most  part,  laid  in  May,  June  and  early  July,  and  the  adult 
condition  is  reached  early  the  next  year,  though  variation  from  this  is  frequent. 
The  young  scales  attack  the  leaves  generally,  but 
later  pass  to  the  twigs.  The  injury  they  cause  by 
removing  the  sap  from  the  tree  is  increased  by 
the  honey-dew  they  secrete,  which  falling  in  large 
amounts  on  fruit  and  leaves,  forms  an  excellent 
material  in  which  a  sooty  fungus  grows,  and 
more  or  less  cuts  off  light  from  the  leaf  surface, 
thus  affecting  the  growth,  and  may  also  clog  the 
stomata  or  breathing  pores  on  the  leaves,  besides 
causing  the  fruit  to  look  objectionable  and  need 
cleaning  before  its  sale.  Control  of  this  pest  is 
by  Hydrocyanic  acid  fumigation  between  Septem- 
ber 1st  and  January  1st.  Several  parasites  and 
enemies  are  known.  One  parasite,  imported  from 
South  Africa,  has  at  times  done  excellent  control 
work,  but  has  not  been  continuously  effective. 

The  Terrapin  Scale  (Eulecanium  nigrofasciatum 
Perg.). — This  is  a  native  insect  attacking  various 
shade  and  fruit  trees.  The  scale  of  the  female  is 
nearly  hemispherical  in  form,  about  one-sixth  of 
an  inch  in  diameter,  reddish,  mottled  and  streaked 
with  black  (Fig.  213).  This  insect  is  viviparous, 
the  young  appearing  in  June  and  July  and  be- 
coming adult  the  following  spring.  The  young 
spend  a  part  of  their  life  on  the  leaves  before 
migrating  to  the  stems.  Control,  when  necessary, 
is  by  spraying  just  before  the  buds  open  in  spring 
with  miscible  oil,  using  5  parts  of  this  and  3  parts 
of  gasoline  thoroughly  emulsified,  and  92  parts  of 
water. 

The  Cottony  Maple  Scale  (Pulvinaria  vitisL.). 
This  insect  attacks  maple,  linden,  and  other 
shade  trees  and  plants.  The  scale  of  the  adult 
female  is  rather  flat,  about  one-fourth  of  an  inch 
in  diameter,  and  by  midsummer  generally  lifted 
at  one  end  from  the  twig  it  is  on,  by  a  projecting  mass  of  cotton-like  threads 
which  surround  2,000  to  3,000  eggs  (Fig.  214).  These  soon  hatch  and  the  young 
crawl  to  the  leaves  and  cover  themselves  with  a  thin  waxy  coating.  In  fall  they 
migrate  to  the  twigs  for  the  winter  and  become  adult  the  following  spring.  When 
abundant  the  large,  white,  cotton-like  masses  make  this  a  very  noticeable  insect. 
Contro  is  by  spraying  with  a  miscible  oil,  1  part,  water  15  parts,  just  before  the 
buds  open  in  the  spring,  or  with  kerosene  emulsion,  stock  1  part,  water  3  parts. 


FIG.  213.— Terrapin  Scale 
(Eulecanium  nigrofasciatum 
Targ.),  reduced  somewhat 
(right  hand  figure),  and  some- 
what enlarged  (left  hand 
figure).  (From  Houser,  Ohio 
Agr.  Exp.  Sta.  Bull.  332.) 


218 


APPLIED  ENTOMOLOGY 


The  Hemispherical  Scale  (Saissetia  hemisphoerica  Targ.). — This  scale  is 
usually  found  in  greenhouses  and  on  house  plants,  such  as  ferns,  palms,  orna- 
mental asparagus,  etc.,  and  also  out  of  doors  in  the  South.  It  is  very  convex,  but 
rather  oval  than  hemispherical,  about  one  -eighth  of  an  inch  long,  brown  in  color. 
The  partly  grown  young  are  very  flat  and  with  a  notch  at  the  hinder  end.  The 
eggs  are  laid  during  about  a  3-month  period  in  late  spring,  thus  resulting  in  the  ap- 
pearance of  young  during  a  long  time.  Fumigation 
as  for  the  Black  Scale,  or  dipping  the  plant  in  whale- 
oil  soap  1  lb.,  water  2  gal.,  and  after  an  hour  rinsing 
the  plant  by  dipping  it  in  water,  are  fairly  effective 
treatments. 

Mealy  Bugs 

Mealy  Bugs  move  about  more  or  less  freely 
during  their  life,  as  their  limbs  are  not  lost  to 
any  extent  by  degeneration.  Nor  is  a  scale 
present,  the  body  being  generally  well  covered 
by  long,  waxy  threads,  though  in  some  cases 
waxy  secretions  forming  plates  connected  with 
the  body  are  produced. 

These  insects  are  inhabitants  of  warm  cli- 
mates and  in  the  North  are  found  only  in  green- 
houses and  on  house  plants. 


FIG.  214.  FIG.  215. 

FIG.  214. — Cottony  Maple  Scale  (Pulvinaria  mtis  L.),  about  half  natural  size. 
(Modified  from  Felt,  N.  Y.  State  Mus.  Mem.  8.) 

FIG.  215. — Citrus  Mealy  Bug  (Pseudococcus  citri  Risso.),  enlarged. 

The  Citrus  Mealy  Bug  (Pseudococcus  citri  Risso). — This  insect  attacks  many 
plants  and  is  a  serious  pest  on  citrus  plants,  feeding  on  the  roots,  stems,  leaves 
and  fruit,  gathering  in  large  clusters  on  the  last.  It  produces  a  large  amount  of 
honey-dew,  on  which  the  sooty  fungus  already  referred  to  grows.  The  adult 
females,  pale  yellow  in  color  and  well  covered  by  a  th  ck  waxy  secretion  (Fig.  215), 
are  one-fourth  of  an  inch  long.  The  300  to  500  eggs  are  laid  in  loose,  white  cotton- 
like  masses,  chiefly  during  fall  and  winter,  and  young  and  adults  move  about 
freely,  the  former  becoming  adult  before  the  following  summer.  The  cottony  wax 
covering  the  insects  renders  them  particularly  difficult  to  reach  with  sprays. 
The  best  spray  thus  far  found  is  a  carbolic  acid  emulsion.  To  prepare  this  take 
8  gal.  of  water  and  boil,  adding  8  lb.  of  soap.  After  this  has  dissolved,  add  1  lb. 
crude  carbolic  acid  and  boil  15  to  20  min.,  which  will  give  a  thick,  creamy  emul- 
sion. To  spray,  dilute  I  gal.  of  this  with  20  gal.  of  water.  Spray  between 


THE  HOMOPTERA 


219 


October  and  March.  Hydrocyanic  acid  fumigation  has  also  given  satisfactory 
results,  especially  with  light  doses  frequently  repeated.  A  number  of  natural 
enemies  are  of  some  value  against  this  insect. 

The  Long-tailed  Mealy  Bug  (Pseudococcus  longispinus  Targ.). — This  is 
often  found  in  greenhouses  attacking  many  kinds  of  plants.  The  bodies  of  adult 
females  vary  from  yellow  to  gray,  and  the  young  are  born  alive,  there  being 
apparently  several  generations  each  year.  Hydrocyanic  acid  fumigation  seems 
to  be  the  most  successful  treatment  for  these  insects.  Nicotine  sulfate  may 
also  be  used. 

The  Cottony  Cushion  Scale  or  Fluted  Scale  (Icerya  purchasi  Mask.).— 
This  serious  pest  of  citrus  and  many  other  plants,  apparently  reached 
California  from  Australia  about  1868  and  by  1880  had  spread  all  over 
the  citrus-growing  regions  of  the  State  and  was  threatening  the  destruc- 
tion of  the  entire  citrus  fruit  industry. 


FIG.  216. — Cottony  Cushion  Seale  (Icerya  purchasi  Mask.)  and  its  lady  beetle  enemy, 
the  Vedalia  (Novius  cardinalis  Muls.):  a,  larvae  of  the  Vedalia  feeding  on  a  Seale;  b,  pupa 
of  the  Vedalia;  c,  adult  Vedalia;  d,  twig  with  the  Scales  and  lady  beetles,  a,  greatly 
enlarged;  real  length  of  6  and  c  shown  by  hair  lines;  d  about  natural  size.  (From  Sanderson 
and  Jackson,  Elementary  Entmology:  after  Marlatt,  U.  S.  D.  A.) 

Investigation  showed  that  in  Australia  it  had  an  enemy  known  as 
the  Vedalia  (Novius  cardinalis  Muls.),  a  lady  beetle,  and  these  were 
finally  brought  to  California  and  colonized  in  the  orange  groves,  where 
they  attacked  the  scales  so  effectively  that  in  the  course  of  a  few  years 
these  were  brought  under  control,  and  now  only  an  occasional  local 
outbreak  makes  the  scale  of  importance.  When  this  happens,  the  in- 
troduction of  the  lady  beetles  to  that  region  is  soon  sufficient  to  check 
all  injury.  In  later  years  the  scale  has  appeared  in  Portugal,  South 
Africa  and  elsewhere,  and  when  the  introduction  of  the  Vedalia  into  those 
regions  has  successfully  followed,  the  scale  has  soon  become  relatively 
unimportant. 

The  female  scale  has  a  red,  yellow  or  brown  body.     It  lays  its  400 


220  APPLIED  ENTOMOLOGY 

to  1,000  eggs  in  a  large  cottony  mass  formed  at  the  hinder  end  of  the 
body,  the  upper  surface  of  the  mass  being  grooved  or  fluted  (Fig.  216). 
There  are  several  generations  in  a  season. 

Several  of  the  scale  insects  treated  in  this  chapter  furnish  good  illustra- 
tions of  the  way  in  which  nature  works  to  preserve  a  balance  in  the 
insect  world.  In  the  first  place  it  should  be  noticed  that  our  native 
scales  are  often  found  with  tiny  circular  holes  in  them  showing  where 
parasites  after  having  fed  on  the  insect  beneath,  have  made  their  escape. 
Other  scales,  long  in  this  country,  such  as  the  Oyster-shell  Scale,  now 
have  numerous  parasites,  some  of  which  are  also  enemies  of  other  kinds 
of  scales,  and  in  fact  may  be  considered  as  scale  enemies  in  general,  or  at 
least  of  most  scales  of  the  same  section.  New  parasites  also  appear 
from  time  to  time  as  enemies  of  scales,  such  as  a  tiny  insect,  Prospaltella 
perniciosi  Tower,  first  discovered  about  1912,  which  at  times  has  done 
remarkably  good  work  against  the  San  Jose  Scale.  But  when  a  new 
scale  or  other  insect  native  elsewhere,  establishes  itself  in  this  country, 
one  of  the  factors  at  least  in  its  success  here,  must  be  that  none  of  its 
parasites  in  the  locality  whence  it  came,  accompanied  it  in  its  transfer. 
If  under  these  circumstances,  climatic  and  other  conditions  prove 
satisfactory,  we  have  a  case  of  an  insect  set  free  from  all  restraint,  to 
work  its  destruction  with  no  check,  at  least  until  some  insect  already 
present  shall  select  it  as  a  new  and  satisfactory  food.  This  was  evidently 
the  case  with  Prospaltella  and  the  San  Jose  Scale,  already  mentioned. 
In  the  meantime,  however,  years  of  destruction  may  elapse  before  any 
such  check  will  appear,  and  the  possibility  of  obtaining  its  special  enemies 
from  its  native  country  appears  to  offer  much  in  the  way  of  quick  relief. 
This  "bug  vs.  bug"  idea  as  it  has  been  called,  has  a  strong  appeal  to  those 
suffering  losses  from  the  attacks  of  a  newly  introduced  pest,  and  it  has 
therefore  been  widely  exploited. 

Probably  the  first  attempt  to  carry  out  this  idea  was  the  introduction 
of  the  Vedalia  for  the  Cottony  Cushion  Scale,  and  in  this  case  an  un- 
qualified success  resulted.  On  the  other  hand,  the  attempt  to  establish 
the  Chinese  Lady  Beetle  in  this  country  to  control  the  San  Jose  Scale 
has  thus  far  been  a  failure,  and  the  introduction  of  the  parasite  Scutel- 
lista  cyanea  Motsch.  to  work  on  the  Black  Scale  cannot  be  regarded  as 
more  than  partially  effective.. 

The  danger  of  introducing  along  with  the  parasite,  its  own  parasites 
(secondary  parasites)  at  such  a  time  is  great,  and  therefore  this  work 
should  be  attempted  only  by  those  especially  trained  for  it. 

All  in  all,  the  "bug  vs.  bug"  idea  is  one  which,  though  always  having 
many  possibilities  of  success,  is  also  one  which  will  often  fail,  and  there- 
for cannot  be  relied  upon  as  a  certain  panacea  for  troubles  caused  by 
introduced  pests. 


CHAPTER  XXVII 
THE  NEUROPTERA 

The  insects  placed  in  this  group,  though  quite  similar  in  structure, 
differ  markedly  in  appearance  in  many  cases.  They  vary  much  in  size, 
ranging  from  less  than  a  quarter  of  an  inch  to  several  inches  in  length, 
and  their  wings  may  be  small  or  large. 

The  mouth  parts  are  for  chewing  or  biting,  and  most  of  the  group 
feed  upon  insects  and  other  small  animals.  The  wings  are  four  in  num- 
ber, well  supplied  with  both  longitudinal  and  (with  a  few  exceptions) 
cross-veins.  The  larvae  in  general  are  active,  moving  about  in  search 
of  their  prey.  A  few  though,  live  in  the  egg  sacs  of  spiders,  feeding  on 
the  young  spiders,  and  in  one  or  two  cases,  fresh-water  sponges  appear 
to  be  their  food.  There  is  a  quiet  pupa  stage. 

The  group  may  be  characterized  as: 

Insects  which  when  adult  have  two  pairs  of  wings  usually  large  as  com- 
pared with  the  body  and  with  numerous  longitudinal  and  (in  most  cases) 
cross-veins.  Mouth  parts  for  chewing.  Metamorphosis  complete. 

So  far  as  is  known,  none  of  the  Neuroptera  are  injurious  insects  and 
some  at  least  are  decidedly  beneficial.  About  half  a  dozen  families  are 
usually  recognized  and  some  of  these  are  here  considered,  either  because 
of  their  economic  importance  or  because  they  are  large  and  common 
enough  to  frequently  attract  attention. 

In  the  family  Sialidae  belongs  the  largest  member  of  the  order  (Fig. 
217)  foilnd  in  the  United  States.  This  is  commonly  called  the  Corydalis 
or  Hellgrammite  (Corydalis  cornuta  L.)  which  is  quite  common  throughout 
the  country  except  in  arid  regions.  The  mandibles  of  the  male  are 
nearly  an  inch  long,  slender  and  somewhat  curved;  those  of  the  female 
are  short.  The  distance  from  tip  to  tip  of  the  wings  when  these  are 
extended,  may  be  over  five  inches,  and  the  size  of  the  insect  and  the  long 
jaws  of  the  male  have  led  to  the  mistaken  belief  that  this  really  harmless 
animal  is  dangerous.  The  egg  are  laid  in  large  masses  on  objects  which 
hang  over  the  water,  into  which  the  larvae  enter  on  hatching,  making 
their  way  under  stones  where  they  feed  for  nearly  3  years  on  the  nymphs 
of  May-flies  and  other  insects.  Here  they  are  searched  for  by  fishermen 
to  use  as  bait,  and  are  usually  called  "Dobsons."  When  full-grown  the 
larva  makes  a  cell  under  some  stone  close  to  the  stream  and  pupates 
for  about  a  month,  after  which  the  adult  escapes  . 

221 


222  APPLIED  ENTOMOLOGY 

Smaller  species,  some  with  gray,  black,  or  black  wings  spotted  with 
white,  belong  here.  They  are  often  quite  common  around  streams  and 
ponds  during  the  summer  months  and  are  frequently  called  " Fish-flies." 


Fio.  217.- — Adult    Corydalis,    about   natural   size   and   its    larva.      (From   Sanderson   and 
Jackson,  Elementary  Entmology;  after  Comstock.) 

The  members  of  the  family  Chrysopidse  are  of  great  economic  im- 
portance as  the  larvae  feed  freely  on  injurious  insects,  particularly  aphids, 
and  are  so  voracious  that  they  are  often  called  Aphis-lions.  The  adults 
(Fig.  218)  are  rather  small,  slender-bodied  insects  averaging  less  than  an 


FIG.  218. — Adult  Lacewing  (Chrysopa  plnrabunda  Fitch),  slightly  reduced.      (From  Folsom.) 

inch  long,  with  long  antennae  and  large,  finely-veined,  green  wings,  which 
when  not  in  use  are  carried  sloping  over  the  body.  These  adults  are 
sometimes  called  "  Golden-eyes "  because  of  their  shining,  golden-yellow 
eyes,  but  perhaps  more  frequently  " Lace-wings"  from  the  delicacy  and 
beauty  of  these  structures. 


THE  NEUROPTERA  223 

The  Lace-wings  are  found  practically  everywhere  in  this  country 
and  are  usually  quite  abundant.  They  lay  their  eggs  on  the  stems, 
branches,  and  leaves  of  plants,  first  constructing  a  slender  but  quite  stiff 
stalk  of  silk  about  half  an  inch  long,  to  the  end  of  which  the  egg  itself  is 
attached  (Fig.  219).  These  eggs  are  usually  placed  in  groups  and  it  is 
believed  that  were  the  eggs  not  raised  on  stalks  out  of  reach,  the  first 
larva  to  hatch  would  at  once  proceed  to  eat  the  eggs  as  its  first  meal. 


FIG.  219. — Eggs    of    a    Lacewing,     greatly    enlarged.      (From    Sanderson    and    Jackson, 
Elementary  Entmology;  after  S.  G.  Hunter.) 


These  larvae  are  rather  short,  somewhat  oval  in  outline,  and  have  long 
mandibles  with  which  they  grasp  their  prey.  The  lower  side  of  each 
mandible  is  grooved  and  the  maxilla  of  the  same  side  is  so  modified  as  to 
fit  into  this  groove  and  convert  it  into  a  tube.  An  insect  attacked  by  an 
Aphis-lion  is  seized  by  the  tips  of  the  jaws  and  its  blood  is  drawn  through 
the  tubes  into  the  body  of  its  captor. 

Aphis-lions  are  often  found  in  colonies  of  plant  lice  which  have  by  their 
feeding  caused  leaves  to  curl,  and  with  an  abundant  food  supply  thus 
provided,  the  insect  is  both  protected  by  the  leaf  and  insured  of  the  food 
it  needs  for  its  development. 

When  full-grown  the  Aphis-lion  forms  around  its  body  a  white,  shin- 
ing, spherical  silken  cocoon  in  which  it  pupates.  When  this  process  is 
complete  the  adult  cuts  out  a  circular  piece  of  the  cocoon,  forming  a  hole 
through  which  it  escapes. 

The  importance  of  Lace-wings  as  friends  of  man  is  such  that  they 
should  be  protected  and  not  destroyed  under  the  impression  that  being 
among  known  pests  they  must  also  be  for  that  reason  injurious. 


224 


APPLIED  ENTOMOLOGY 


In  the  Western  States  are  a  few  insects  belonging  to  the  Neuroptera,  and 
family  Raphidiidae.  They  are  small,  less  than  an  inch  in  length,  but  with  an 
unusually  long  prothorax  (Fig.  220).  The  larvae  feed  on  other  insects  and, 
among  others,  on  codling  moth  larvae.  They  occur  chiefly  under  loose  bark  in 
this  stage,  and  while  not  as  abundant  as  could  be  desired,  do  good  work  by  attack- 
ing many  injurious  species.  They  have  been  introduced  into  Australia  in  the 
hope  that  they  may  become  effective  enemies  of  the  codling  moth  there. 


FIG.  220.  FIG.  221. 

FIG.  220. — Adult  Raphidian  (Raphidia  oblita  Hagen),  about  twice  natural  size. 
(Original.) 

FIG.  221. — Adult  Mantispa  (Mantispa  brunnsa  Say)  showing  grasping  front  legs. 

Somewhat  enlarged.  (Original.) 

Another  family,  the  Mantispidae,  though  few  in  numbers,  has  its  members 
quite  widely  distributed.  The  Mantispas  (Fig.  221)  as  they  are  called,  like  the 
Raphidians,  have  a  greatly  elongated  prothorax  and  their  fore  legs  are  also  long 
and  adapted  to  grasping  their  prey.  The  adults  are  larger  than  the  Raphidians, 
being  about  an  inch  in  length  and  with  long  wings.  Though  feeding  on  other 
insects,  most  of  which  are  likely  to  be  injurious,  the  Mantispas  are  not  numerous 
enough  to  be  of  any  great  importance. 


FIG.  222. 

FIG.  222. — Adult  Ant-lion  about  natural  size.      (Original.) 
FIG.  223. — Larva  of  an  Ant-lion,  about  twice  natural  size. 


FIG.  223. 


(After  Meinert.) 


The  insects  belonging  to  the  Family  Myrmeleonidse  are  generally 
spoken  of  as  the  Ant-lions,  though  the  name  " Doodle-bug"  is  sometimes 
applied  to  their  larvae.  They  are  widely  distributed  over  the  United 
States,  particularly  in  sandy  places,  but  are  most  abundant  in  the  South. 


THE  NEUROPTERA  225 

Many  kinds  of  the  adults  (Fig.  222)  superficially  greatly  resemble  the 
" damsel-fly"  section  of  the  Dragon-flies  (Odonata),  their  long,  slender 
bodies,  large,  gauzy  wings  and  their  general  size  causing  the  resemblance. 
Their  antennae,  however,  instead  of  being  very  small  and  not  noticeable, 
are  of  fair  size  and  knobbed  at  the  tip,  which  provides  an  easy  way  by 
which  to  distinguish  the  two  groups.  Other  characters  and  their  life 
history  also  prove  that  the  resemblance  is  only  superficial. 

The  larvae  of  the  ant-lions  (Fig.  223)  greatly  resemble  those  of  the 
lace-wings  in  general  form  and  in  the  possession  of  long  jaws  grooved  for 
sucking  the  blood  of  their  victims.  They  excavate  little  conical  pits 
in  soft,  dry,  preferably  sandy  ground,  an  inch  or  two  across  and  as  deep 
as  possible  for  the  sandy  sides  to  hold.  At  the  bottom  of  the  pit  thus  dug 
the  young  ant-lion  buries  itself  except  for  its  head,  and  waits  for  an 
unwary  insect  to  fall  in.  Sliding  down  the  slope  of  loose  earth  the  victim 
literally  falls  into  the  jaws  of  the  waiting  enemy  and  is  killed  and  de- 
voured. It  has  been  stated  that  sometimes  the  insect  on  its  way  down 
the  side  of  the  pit  is  able  to  check  itself  and  start  to  climb  out,  and  that 
then  the  ant-lion  shovels  a  load  of  sand  onto  the  top  of  its  flat  head,  with 
its  leg,  and  snaps  the  sand  up  the  side  of  the  pit,  where  falling,  it  sweeps 
the  prey  down  to  the  bottom  within  reach  of  the  ant-lion! 

The  process  of  excavating  the  pit  is  also  one  of  extreme  interest. 
The  insect  first  traces  out  a  circle  of  the  desired  size,  loading  its  head  with 
sand  from  inside  the  circle  and  snapping  it  out,  and  on  completing  the 
circle,  repeats  the  process  but  in  the  reverse  direction,  and  this  is  continued 
until  the  pit  has  been  completed.  In  doing  this  the  larva  always  moves 
backward. 

After  becoming  full-grown  the  ant-lion  larva  forms  a  spherical  cocoon 
of  sand  and  silk  in  the  ground,  within  which  it  transforms  to  the  adult. 

The  ant-lions,  though  feeding  on  other  insects,  are  of  little  if  any 
economic  importance  as  the  forms  they  are  most  liable,  to  capture  are  not 
often  probably,  serious  pests.  Their  habits  and  manner  of  life,  how- 
ever, are  so  interesting  that  much  attention  has  been  given  to  them  and 
what  has  been  published  about  them  forms  one  of  the  most  interesting 
chapters  of  Entomology. 

The  Neuroptera,  though  widely  distributed  over  the  world,  do  not 
constitute  a  large  group.  Less  than  two  hundred  kinds  are  known  in 
this  country,  and  probably  not  more  than  a  thousand  kinds  in  all  have 
thus  far  been  discovered.  Fossil  specimens  of  several  of  the  families  have 
been  recognized. 


i.-, 


CHAPTER  XXVIII 
THE  TRICHOPTERA 

The  Caddice  (sometimes  spelled  Caddis)  Flies,  as  the  members  of  this 
order  are  usually  called,  are  rather  soft-bodied  insects  ranging  in  size 
from  less  than  an  eighth  of  an  inch  to  an  inch  or  more  in  length.  • 

The  wings,  though  much  reduced  in  a  few  cases,  are  almost  always 
large  and  well  developed,  with  numerous  longitudinal,  but  few  cross-veins. 
They  are  membranous,  the  front  pair  somewhat  leathery,  and  all  are 
more  or  less  densely  covered  with  hairs  which  in  some  species  are  rather 
scale-like  in  form.  The  hind  wings  are  usually  broader  than  the  front 
pair  and  when  not  in  use  are  sometimes  folded  lengthwise.  The  position 
of  all  the  wings  when  at  rest  is  with  their  hinder  margins  together  over  the 
back  of  the  insect  and  their  costas  down  at  the  sides  of  the  body,  upper 
faces  sloping  downward  and  outward  like  a  house  roof  (Fig.  224). 

The  mouth  parts  of  the  adult  are  poorly  developed  though  evidently 
modified  from  the  chewing  type  and  it  is  probable  that  little  if  any  food  is 
taken  in  this  stage.  The  antennae  are  generally  well  developed,  and  in 
some  species  they  may  be  several  times  as  long  as  the  body.  The  legs 
are  quite  long  and  slender. 

The  larvae  (Fig.  225)  somewhat  resemble  small  caterpillars  in  form. 
They  are  nearly  all  found  in  water,  chiefly  that  of  ponds  or  slow-running 
streams,  though  a  few  inhabit  rapid  currents.  The  abdomen  is  soft,  the 
chitinous  skin  being  delicate,  and  the  larvae  therefore  construct  cases  of 
various  materials  as  a  protection  for  this  portion  of  the  body. 

The  Trichoptera  may  be  defined  as : 

Insects  which  as  adults  have  rather  soft  bodies:  four  membranous  wings 
with  numerous,  longitudinal  and  few  cross-veins,  and  more  or  less  closely 
covered  by  hairs,  folded  over  the  body  like  a  house  roof  when  at  rest :  mouth 
parts  rather  rudimentary:  antennae  and  legs  quite  long,  the  former  sometimes 
exceptionally  so.  Larvce  living  in  cases,  nearly  always  in  the  water.  Meta- 
morphosis complete. 

The  adult  Caddice-fly,  though  having  well-developed  wings,  is  not  a 
strong  flier  and  these  insects  are  therefore  most  frequently  found  near 
water. 

The  eggs  are,  at  least  usually,  laid  in  clusters  in  a  mass  of  jelly,  and 
are  probably  dropped  into  the  water.  On  hatching,  the  larvae  begin  the 
construction  of  cases  in  which  to  live.  The  materials  of  which  these  are 

226 


THE  TRICHOPTERA 


227 


made  differ  according  to  the  species  of  Caddice-fly  concerned  and  vary 
greatly  (Fig.  226).  Some  take  pieces  of  leaves  which  have  fallen  into  the 
water;  others  select  veins  of  the  leaves  and  similar  sized  straws  and  put 
them  together  cris-cross,  something  like  the  logs  of  a  log  house;  some 
species  use  the  finest  sand  for  this  purpose; 
others  coarse  gravel,  and  still  others  use  a  mix- 
ture of  long  and  short  pieces  of  plants  so  that 
the  ends  of  the  longer  ones  extend  some  distance 
behind  the  end  of  the  case. 

The  case  itself  is  usually  straight  but  in  some 
species  it  may  be  curled,  and  resembles  a  small 
snail-shell.  Indeed  this  resemblance  is  so  close 
that  in  one  instance  at  least,  such  a  case  was 
actually  described  as  that  of  a  shell!  The  ma- 
terials, whatever  they  may  be,  are  held  together 
by  silk  spun  by  the  larva,  coming  from  silk  glands 
within  the  body  and  poured  out  through  an 
opening  close  to  the  mouth.  Within  the  case 
the  larva  lives,  crawling  about  by  extending  its 


FIG.  224. — Caddice-flies:  adult  at  rest,  above;  with  wings  spread,  below.     Larvae  showing 
three  kinds  of  cases,  crawling.     (From  Linville  and  Kelly,  General  Zoology.) 

head  and  thorax  out  of  the  front  end  so  that  its  feet  can  be  used,  and 
dragging  the  case  along. 

Some  caddice-fly  larvae  make  simpler  houses  than  these.     Such  species 
live  in  rapid  water  and  there  fasten  a  few  tiny  stones  under  rocks  by  their 


228 


APPLIED  ENTOMOLOGY 


silk,  and  between  these  spin  a  silken  tube  in  which  to  live.  Close  to  this 
they  spin  more  or  less  funnel-shaped  webs,  the  mouth  up-stream  and  so 
arranged  that  tiny  animals  swept  down  by  the  current  within  the  outer 
limits  of  the  funnel  come  within  reach  of  the  larva  lying  in  its  tube. 
While  the  food  of  these  larvae  is  carnivorous,  in  most  of  the  species  plant 
materials  are  consumed. 

The  larvae,  in  most  cases,  breathe  by  tracheal  gills  which  are  slender 
filaments,  frequently  grouped  in  clusters,  and  attached  to  the  abdominal 
segments.  Other  structures  present  in  some  species  are  also  suspected  of 
being  concerned  with  respiration. 


'j^^^^^^jj^jl&fjjjj^^^^^ 

r^-V   ™|T 


FIG.  225.  FIG.  226. 

FIG.  225. — Caddice-fly  larvae:  larva  with  head  and  thorax  extended  out  of  its  case, 
above;  larva  removed  from  its  case,  below,  showing  tracheal  gills.  About  twice  natural 
size.  (Modified  from  Leuckart's  Wandtafeln.) 

FIG.  226. — Examples  of  different  types  of  cases  formed  by  Caddice-fly  larvae.  (From 
Sanderson  and  Jackson,  Elementary  Entomology:  after  Furneaux.) 

When  full-grown  the  Caddice-worm  forms  a  sort  of  lid  or  door  grating 
across  the  front  opening  of  its  case^  though  not  complete  enough  to  pre- 
vent water  from  entering  and  supplying  the  insect  with  the  oxygen  it 
needs.  After  pupation  in  its  case  the  adult  swims  to  the  surface  and 
grasps  some  object,  from  which  it  takes  its  flight.  In  some  species  it  is 
apparently  the  pupa  which  when  ready  to  become  the  adult,  comes 
to  the  surface  and  passes  its  final  molt  there. 

The  Trichoptera  is  quite  a  large  group  of  insects  and  representatives 
of  it  are  found  in  almost  all  parts  of  the  world.  Probably  not  many  more 
than  a  thousand  species  have  been  described,  as  they  do  not  appear  to  be 
of  any  economic  importance  unless  their  consumption  of  decaying  vege- 
table matter  in  pools  can  be  considered  as  desirable,  but  it  is  very  likely 
that  there  are  from  five  to  ten  thousand  kinds  in  existence.  Their  cases 
have  been  found  as  fossils  and  adults  have  also  been  preserved  in  this  way. 


THE  TRICHOPTERA  229 

The  Trichoptera  are  evidently  closely  related  to  the  Lepidoptera  in 
many  ways  and  are  undoubtedly  with  the  last-named  order,  divergent 
descendants  from  common  ancestors.  Some  Lepidoptera  so  closely  resem- 
ble Trichoptera  in  fact,  that  they  have  been  placed  in  the  latter  group. 
They  also  have  many  resemblances  to  the  Neuroptera,  but  their  connec- 
tion with  this  order  is  plainly  more  remote,  and  sufficient  time  has  elapsed 
since  the  divergence  of  the  present  Neuroptera  and  Trichoptera  from  their 
common  ancestors,  to  permit  the  development  of  many  differences. 


CHAPTER  XXIX 


THE  LEPIDOPTERA 

The  Lepidoptera  are  the  moths  and  butterflies,  which  form  one  of 
the  largest  and  most  noticeable  groups  of  insects.  Its  members  are 
found  in  all  countries  and  their  large  size  in  many  cases,  their  brilliant 
colors  and  the  habits  of  their  larvae  as  well  as  the  injuries  they  cause, 
have  attracted  much  attention. 

The  adults  have  four,  large,  membranous  wings  in  most  cases  (a  few 
have  lost  their  wings),  more  or  less  completely  covered  by  overlapping 
scales  making  the  wings  opaque  where  these  are  present.  Colors  of  the 

wings  are  due  either  to  the  presence  of 
pigments  in  the  scales:  to  optical  colors 
caused  by  the  surfaces  of  the  scales  break- 
ing up  the  light  striking  them;  or  by  both 
factors  together. 

The  mouth  parts  of  the  adult  are  greatly 
modified  from  those  of  chewing  insects, 
though  enough  remains  to  show  that  the 
ancestors  of  the  group  must  have  fed  by 
chewing.  The  development  of  the  parts 
varies  in  different  species,  some  of  the 
lower  forms  having  as  a  whole,  a  much 
closer  resemblance  to  the  condition  in 
chewing  insects  than  is  the  case  with  most 
of  them.  In  one  group,  the  mouth  parts 
are  sufficiently  of  the  mandibulate  type  to 
enable  the  insects  to  feed  on  pollen. 

In  general  a  labrum  or  front  lip  is  evi- 
dent, but  the  mandibles  are  practically  lost. 
The  maxilla?  are  extremely  modified,  a  por- 
tion of  each  contributing  its  half  to  the  formation  of  a  proboscis  or  tongue 
(Fig.  227).  This  is  a  flexible  organ  varying  greatly  in  length,  its  two 
halves  so  interlocking  as  to  form  a  tube  between  them,  through  which, 
when  completely  developed,  fluids  may  be  drawn  into  the  mouth.  The 
degree  of  development  of  the  proboscis  differs  greatly  in.  different 
Lepidoptera,  and  while  it  is  functional  in  perhaps  the  majority  of  the 
group  it  is  only  partly  developed  or  even  rudimentary  and  useless  in 
others.  Such  Lepidoptera  evidently  do  not  feed  while  adult. 

230 


FIG.  227. — Diagram  of  head  of 
a  Lepidopterous  insect,  showing 
the  tongue.  (From  a  drawing  by 
M.  F.  Webster.) 


THE  LEPIDOPTERA  231 

In  some  cases  the  maxillary  palpus  is  developed :  in  others  it  is  nearly 
or  wholly  lacking.  The  labium  or  hinder  lip  is  also  practically  absent 
except  for  the  labial  palpi  which  are  usually  large,  thickly  covered  by 
hairs  or  scales,  and  project  forward  at  the  sides  of  the  head,  often 
turning  upward  somewhat,  and  partially  or  wholly  concealing  the  pro- 
boscis when  this  is  coiled  up  under  the  head,  the  place  where  it  is  carried 
when  not  in  use. 

The  mouth  parts  of  the  larva  (or  caterpillar  as  it  is  usually  called) 
are  entirely  different.  In  this  stage  they  are  chewing  structures,  similar 
to  those  of  a  grasshopper  in  a  general  way,  and  no  special  description  is 
needed.  '  In  the  center  of  the  end  of  the  labium,  however,  is  a  slender 
projection  called  the  spinneret,  which  at  its  tip  has  the  external  opening 
of  the  duct  leading  to  the  silk  glands. 

The  antennae  of  adult  Lepidoptera  are  usually  quite  long  but  vary 
greatly  in  their  form  in  different  species.  In  the  butterflies  they  are 
slender  but  enlarged  near  the  tip  forming  a  club  (Figs.  309  to  317),  or 
with  this  enlarged  part  bent  into  a  sort  of  hook  (Fig.  308) .  These  forms 
of  antennae  are  almost  never  found  in  the  moths,  where  they  may  be 
simple  and  thread-like;  with  small  hair-like  projections  at  the  side; 
bristles  in  place  of  the  hairs;  clusters  of  the  bristles;  with  tooth-like  or 
saw-like  side  projections;  with  long  projections  on  one  or  both  sides,  in 
the  latter  case  giving  the  antennae  a  feather-like  appearance;  and  other 
forms  also  occur.  (Compare  Figs.  228  to  305). 

The  eyes  are  large,  though  in  some  cases  partly  concealed  by  hairs 
or  scales,  which  as  a  rule  thickly  clothe  the  entire  body.  Ocelli  are  also 
sometimes  present.  On  the  top  of  the  prothorax  a  pair  of  projections  or 
lobes  often  occurs,  called  patagiae,  sometimes  very  large  and  capable  of 
some  movement;  in  others,  smaller  or  even  reduced  to  mere  traces.  On 
the  large  mesothorax  is  a  somewhat  similar  pair  of  structures  called  the 
tegulae  which  extend  backward  over  the  point  where  each  fore  wing 
articulates  with  the  body.  The  abdomen  may  be  long  or  short,  stout 
or  slender,  connected  with  the  thorax  either  by  a  broad  or  a  rather 
constricted  attachment.  The  legs  are  quite  long  and  slender. 

Characters  by  which  the  members  of  this  group  may  be  distinguished 
are: 

Insects  which  as  adults  have  (with  a  few  exceptions)  four  membranous 
wings  more  or  less  completely  covered  by  overlapping  scales:  mouth  parts 
for  sucking.  The  larvae  have  chewing  mouth  parts.  Metamorphosis 
complete. 

The  Lepidoptera  is  such  a  large  order  that  great  differences  in  its 
members  are  very  common.  The  smallest  ones  are  almost  microscopic 
while  the  largest  one  known  may  measure  about  a  foot  between  the  tips 
of  its  expanded  wings.  The  wings  of  each  side,  to  obtain  their  greatest 
efficiency,  are  more  or  less  completely  coordinated  for  flight  by  one 


232  APPLIED  ENTOMOLOGY 

of  three  methods.  In  the  butterflies  and  some  of  the  moths,  the  basal 
portion  of  the  costal  region  of  the  hind  wing  is  enlarged,  forming  a  sort 
of  shoulder  over  which  the  hind  margin  of  the  fore  wing  lies,  thus  enabling 
the  two  to  a  large  extent,  to  function  as  a  single  wing.  In  most  moths, 
however,  instead  of  a  shoulder,  a  rather  long,  curved  bristle  or  cluster  of 
bristles,  called  a  frenulum,  arises  near  the  base  of  the  hind  wing  and  runs 
forward  and  outward,  passing  under  a  small  flap  or  through  a  tuft  of 
scales  on  the  under  side  of  the  fore  wing,  so  that  as  the  two  wings  move  in 
flight,  this  frenulum  slides  backward  and  forward  in  its  track  under  the 
fore  wing  and  holds  the  two  together.  A  third  type  of  connection,  found 
in  only  a  few  moths,  is  a  small  lobe  near  the  base  of  the  hind  margin  of 
the  fore  wing,  which  extends  backward  toward  the  hind  wing.  This  lobe 
is  called  a  jugum  and  is  also  probably  more  or  less  effective  in  producing 
coordination  in  the  use  of  the  wings. 

The  number  and  arrangement  of  the  wing  veins  is  of  great  importance 
in  the  Lepidoptera,  much  of  the  classification  in  this  order  being  based 
upon  these  structures.  The  main  veins  (see  Fig.  20)  are  of  course, 
longitudinal,  starting  at  the  point  of  attachment  of  the  wing  to  the  body 
and  diverging  toward  its  outer  margin,  some  of  them  branching  several 
times.  Cross-veins  are  very  few,  however,  and  consequently  there  are 
only  a  few  closed  cells  (see  page  13),  and  some  at  least  (perhaps  all) 
of  these  are  produced  by  the  fusion  of  branches  of  longitudinal  veins, 
rather  than  by  true  cross-veins. 

Various  ways  of  designating  the  veins  and  their  branches  have  been 
offered,  but  these  are  best  comprehended  in  connection  with  laboratory 
work  on  the  insects  themselves,  and  are  therefore  not  given  here. 

The  eggs  of  Lepidoptera  vary  greatly  in  form  and  also  in  color. 
They  may  be  elongate,  spherical,  flattened,  scale-like,  or  of  other  forms, 
and  the  shell  or  chorion  may  be  smooth  or  sculptured  with  ridges  and 
reticulations.  The  eggs  may  be  laid  singly  or  in  clusters  and  may  or 
may  not  be  covered  with  hairs  from  the  body  of  the  parent  moth,  or 
with  a  secretion  which  conceals  them  from  view.  They  may  hatch  in 
a  few  days  or  after  longer  periods,  in  some  cases  many  months.  The 
adults  have  no  ovipositor  so  the  eggs  are  always  laid  on  the  surface 
of  the  place  of  deposition,  though  if  the  abdomen  of  the  insect  be  small, 
this  may  be  in  a  small  crack  or  other  opening. 

The  larvae  produced  by  the  hatching  of  the  eggs  are  called  cater- 
pillars and  have  no  resemblance  whatever  to  the  adults  they  are  to 
become.  They  are  usually  rather  worm-like  animals,  with  a  generally 
recognizable  head  and  a  body  consisting  of  a  series  of  rather  similar  seg- 
ments, the  first  three  of  which  correspond  to  the  thorax  of  the  adult  and 
almost  always  bear  six  legs.  Some  of  the  following  segments  will  also 
have  legs  but  these  are  totally  different  in  structure  from  the  others  and 
are  merely  temporary  in  their  nature,  designed  to  support  this  portion  of 
the  body. 


THE  LEPIDOPTERA  233 

The  internal  structures  of  the  caterpillar  do  not  differ  greatly  in  their 
arrangement  from  those  of  an  adult  insect,  except  that  the  reproductive 
organs  are  only  slightly  developed  at  this  time,  and  in  the  presence 
along  each  side  of  the  body  of  a  silk  gland,  large  in  those  which  will 
later  need  large  quantities  of  silk,  but  present  in  all.  A  duct  from  each 
gland  runs  forward  to  the  mouth  where  the  two  unite  and  open  to  the 
exterior  through  the  spinneret  already  referred  to. 

Most  caterpillars  feed  on  plants  or  vegetable  material.  Their  work 
is  noticed  chiefly  by  their  stripping  plants  of  their  leaves,  though  some 
bore  in  stems,  roots,  fruit,  seeds  or  other  parts.  A  few  attack  feathers, 
silk,  etc.;  but  this  is  not  the  general  habit.  The  larval  stage  may  last 
only  a  few  days  for  some  species  but  is  generally  a  month  or  more,  and 
some  feed  during  the  fall,  become  quiet  during  the  winter,  and  complete 
their  feeding  the  following  spring. 

A  large  majority  of  the  caterpillars  are  termed  naked,  having  only 
a  few  tiny  spines  or  hairs,  not  large  enough  to  be  noticeable.  From 
this  condition  every  grade  of  density  of  covering  occurs,  to  species  entirely 
covered  by  long,  thickly  placed  hairs  which  give  the  animal  a  hairy  or 
"  woolly  "  appearance.  Some  have  large  warts  or  horns  on  the  thorax  or  a 
sort  of  horn  above,  near  the  hinder  end  of  the  body. 

Their  colors  also  vary  greatly,  some  being  brightly  colored  while 
others,  green,  either  with  or  without  white  streaks,  appear  to  seek  con- 
cealment by  their  resemblance  to  the  leaves  on  which  they  feed.  Those 
living  in  protected  situations,  such  as  in  plant  stalks,  are  nearly  white: 
cutworms  which  pass  the  day  in  the  ground  are  dark  as  a  rule,  with 
rather  faint  markings. 

When  the  caterpillar  has  become  full-grown  it  generally  leaves  the 
place  where  it  was  feeding  and  in  some  satisfactory  location,  spins  a 
cocoon  around  itself,  using  for  this  purpose  the  silk  produced  by  its 
silk  glands.  In  some  species  the  cocoon  is  very  complete,  thick,  tough, 
and  entirely  conceals  the  larva  within.  On  the  other  hand,  there  are 
cocoons  where  only  sufficient  silk  is  used  to  attach  the  insect  and  hold  it 
in  place ;  and  between  these  extremes  all  degrees  of  cocoon  construction 
occur.  Sometimes  leaves,  hairs  from  the  body  of  the  caterpillar,  or  dirt 
when  the  insect  enters  the  ground  at  this  stage,  are  incorporated  in  the 
cocoon. 

Within  the  cocoon  the  caterpillar  molts,  leaving  its  cast-off  skin  at 
one  end.  The  result  of  this  molt  is  a  pupa,  its  form  showing  through 
its  new  skin  which  is  generally  brown,  the  outlines  of  the  adult  body 
and  its  appendages  including  the  wings  being  evident,  these  last,  however, 
very  small  as  there  would  be  no  room  for  the  full-sized  wings  of  the  adult 
within  the  cocoon.  Internal  changes  and  the  completion  of  such  external 
ones  as  are  necessary,  now  proceed  until  the  adult  insect  has  been  entirely 
formed,  and  is  ready  to  escape.  When  this  happens  another  molt  re- 


234  APPLIED  ENTOMOLOGY 

leases  the  insect  from  the  brown  outer  pupa  skin,  and  either  before  or 
after  this,  an  opening  in  the  cocoon  is  made  and  the  adult  emerges. 
It  then  crawls  up  on  something  and  remains  quiet  for  a  while;  its  wings 
being  free  to  expand,  increase  rapidly  till  of  their  full  size;  the  surplus 
fluids  in  the  body  are  expelled,  and  after  an  hour  or  two  the  insect  is 
ready  for  flight. 

While  for  most  Lepidoptera  this  outline  of  development  is  in  general 
correct,  in  the  butterflies  we  find  that  cocoon  making  is  limited  to  attach- 
ing the  hinder  end  of  the  body  by  silk,  to  the  object  on  which  it  is  to 
pupate,  and  the  formation  of  a  silken  loop  around  its  body  to  hold  it  up. 
Such  a  pupa,  producing  a  butterfly,  is  usually  given  the  special  name 
" chrysalis."  (See  Fig.  317/). 

Besides  the  names  " butterflies"  (Rhopalocera),  and  " moths" 
(Heterocera)  used  to  distinguish  different  sections  of  the  Lepidoptera, 
we  also  have  the  terms  "Microlepidoptera"  or  small  moths,  and  "Macro- 
lepidoptera"  or  large  ones.  These  are  wholly  relative  and  rather  indefi- 
nite, but  are  nevertheless  convenient  in  spite  of  the  fact  that  it  would  be 
doubtful  under  which  head  to  designate  many  species  of  the  order. 

The  latest  list  of  the  insects  of  this  order  found  in  North  America 
places  them  in  about  70  families,  but  there  are  more  of  these  divi- 
sions in  other  parts  of  the  world.  Some  of  the  families  include  many 
species  and  insects  of  much  economic  importance,  while  others  have 
only  a  very  few.  Only  the  more  important  families,  either  in  size  or 
because  of  the  pests  they  contain,  are  included  here. 

Family  Cossidae  (Carpenter  Moths). — The  larvae  of  the  moths  belonging  in 
this  family  bore  in  trees  and  are  sometimes  quite  injurious.  There  are  several 
native  species,  the  most  common  being  the  Carpenter  Worm  or  Goat  Moth 
(Prionoxystus  robinics  Peck)  which  lays  its  eggs  in  the  crevices  of  the  bark  of 
various  trees.  The  larva?  bore  in  the  limbs  injuring  or  killing  them,  and  the 
entire  life  history  is  believed  to  take  3  years.  The  adults  which  appear  in  June 
and  July  are  quite  large,  the  wings  of  the  female  spreading  about  three,  and  those 
of  the  male  about  two  inches.  The  wings  are  mottled  light  and  dark  gray,  except 
the  hind  wings  of  the  male  which  are  yellow.  The  Leopard  Moth  ( Zeuzera 
pyrina  L.),  a  European  pest  belonging  in  this  family,  reached  this  country  before 
1879  and  now  occurs  along  the  Atlantic  Coast  from  New  Hampshire  to  Delaware 
and  a  rather  short  distance  inland.  The  wings  of  the  moths  (Fig.  228)  spread  from 
one  to  about  two  inches  and  are  white  with  numerous  black  spots.  The  thorax 
has  seven  black  spots  above.  The  moths  appear  from  May  till  September  and  lay 
their  eggs  on  the  bark,  several  hundred  in  all,  but  usually  only  a  few  at  a  place. 
The  caterpillars  (Fig.  229)  are  liable  to  enter  the  small  twigs,  but  may  enter  else- 
where, and  bore  through  the  wood.  Small  twigs  are  killed  and  larger  ones  weak- 
ened and  in  time  may  also  be  destroyed  by  this  boring,  and  if  the  branch  becomes 
too  small  at  any  time  for  the  larva,  it  will  leave  it  for  a  larger  one.  Injured 
limbs  are  often  so  weakened  as  to  break  off  during  storms.  The  borer  feeds  during 
parls  of  three  seasons,  pupating  in  its  burrow  the  third  spring.  It  is  more 
abundant  in  and  near  cities  and  towns  than  in  the  open  country 


THE  LEPIDOPTERA 


235 


The  work  of  borers  of  this  group  is  often  evidenced  by  fine  chips,  excrement 
or  frass  pushed  out  of  the  entrances  to  the  tunnels;  by  wilted  leaves;  by  tunnels 


f 


FIG.  228. — Adult  female  (left)  and  male  (right)  of  the  Leopard  Moth  (Zeuzera  pyrina  L.) 
about  natural  size.     (From  Britton,  Eleventh  Kept,  Ent.  Conn.  Agr.  Exp.  Sta.  1911.) 


FIG.  229. — Larva  of  Leopard  Moth  in  its  burrow.     Natural  size.     (From  Britton,  Eleventh 
Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1911.) 

in  fallen  branches,  and  by  splits  and  breaks  in  the  bark  when  the  larvae  work  just 
beneath  it. 


236  APPLIED  ENTOMOLOGY 

Control  for  the  Leopard  Moth  and  for  Carpenter  Moths  in  general  is  to  locate 
the  entrance  holes  of  the  larvae  and  inject  a  little  carbon  disulfid  into  them,  then 
stopping  the  opening  with  putty,  mud  or  wax.  Thoroughly  infested  trees  should 
be  cut  and  burned  during  the  cold  months,  to  destroy  the  caterpillars  in  them, 
as  such  trees  are  doomed  in  any  case. 

Family  Tineidae  (Tineids). — The  insects  belonging  in  this  family 
are  all  Microlepidoptera,  the  distance  between  the  tips  of  their  wings 
when  spread  being  generally  much  less  than  an  inch.  They  are  not 
noticeable  insects  and  only  a  few  are  of  great  importance.  Three, 
however,  are  serious  household  pests  and  cause  much  injury,  being  the 
species  commonly  called  Clothes  Moths,  all  natives  of  Europe  but  for 
many  years  now,  present  in  this  country. 

The  Case-making  Clothes  Moth  (Tinea  pellionella  L.). — This  is  the 
most  generally  distributed  of  the  three  species  and  is  the  most  common 
one  in  the  North.  The  moth  flies  at  night  and  may  frequently  be  seen  in 


FIG.  230.  FIG.  231. 

FIG.  230. — Adult  of  Case-making  Clothes  Moth  (Tinea  pellionella  L.)  four  times  natural 
size.  (From  Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan 
Company,  Publishers.) 

FIG.  231. — Case  of  the  Case-making  Clothes  Moth,  three  times  natural  size.  (From 
Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan  Company, 
Publishers.) 

infested  houses  flying  about  the  rooms  but  not  attracted  to  any  light 
there  may  be  present.  In  fact,  if  during  June,  July  or  August  any  tiny 
moth  flies  to  the  light  in  a  room  at  night,  that  fact  is  of  itself  evidence  that 
the  insect  is  not  a  clothes  moth. 

The  adult  (Fig.  230)  is  grayish-yellow  with  faint  spots,  its  hind  wings 
more  nearly  a  silvery  gray.  It  spreads  about  half  an  inch.  The  eggs  are 
generally  laid  on  woolen  goods  of  any  kind,  furs  or  feathers.  They 
hatch  in  about  10  days  and  each  larva  constructs  a  case  (Fig.  231)  made  of 
particles  of  the  materials  on  which  it  feeds,  lined  with  silk,  and  with  its 
body  in  the  case,  crawls  about,  feeding  as  it  goes.  As  it  grows  and  the 
case  becomes  too  small,  the  caterpillar  enlarges  it  and  when  full-grown 
attaches  it  to  some  object  and  pupates  in  it,  the  moth  emerging  about 
3  weeks  later.  In  the  North  there  usually  seems  to  be  but  one  generation 
a  year  but  in  the  South  there  are  two  and  possibly  more. 

The  Webbing  Clothes  Moth  (Tineola  biselliella  Hum.). — This  species, 
though  found  in  the  North,  is  most  common  in  the  South.  The  adult 


THE  LEPIDOPTERA  237 

(Fig.  232)  is  of  about  the  same  size  as  that  of  the  last-described  species, 
but  its  fore  wings  are  uniformly  yellowish.  There  are  two  generations 
each  year.  The  caterpillar  feeds  on  the  same  materials  as  that  of  the 
Case-making  Clothes  Moth  and  has  also  been  known  to  eat  cobwebs, 
dried  specimens  of  insects  and  beef  meal.  It  does  not  form  a  case  but 
spins  a  sort  of  web  of  silk  as  it  moves  about.  When  ready  to  pupate 
it  forms  a  cocoon  of  silk  to  which  particles  of  wool  or  whatever  it  has  been 
feeding  on,  are  added. 


FIG.  232.  FIG.  233. 

FIG.  232. — Adult  of  the  Webbing  Clothes  Moth  (Tineola  biselliella  Hum.),  four  times 
natural  size.  (From  Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the 
Macmillan  Company,  Publishers.) 

FIG.  233. — Adult  of  the  Tapestry  Moth  (Trichophaga  tapetzella  L.),  three  times  natural 
size.  (From  Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the  Macmillan 
Company,  Publishers.) 

The  Tapestry  Moth  (Trichophaga  tapetzella  L.). — The  Tapestry  Moth 
is  not  as  common  in  this  country  as  the  other  two  clothes  moths,  and  is 
a  larger  insect  (Fig.  233),  spreading  about  three-quarters  of  an  inch.  It 
seems  to  prefer  to  attack  heavier  and  coarser  cloths  than  the  other  species, 
as  well  as  felts,  skins,  etc.,  and  is  found  in  carriage  upholstering  and  similar 
places,  as  often  as  in  houses.  The  caterpillar  tunnels  in  its  food,  lining 
the  galleries  somewhat  with  silk,  and  in  these  galleries  it  also  pupates. 

Control  for  Clothes  Moths. — All  woolen  goods,  furs,  feathers,  rugs  and 
similar  materials  not  in  regular  use  during  the  summer  should  be  care- 
fully aired  in  the  sun  as  long  as  possible,  and  brushed,  beaten  or  shaken 
thoroughly  before  being  put  away  in  the  spring.  They  should  then  be 
placed  in  tight  trunks,  boxes  or  bags  either  of  cloth  or  paper.  After 
being  thus  treated  they  should  be  safe  for  the  summer,  provided  no 
eggs  nor  larvae  have  escaped  and  are  still  present  in  the  materials.  But 
a  surer  method  is  to  thoroughly  fumigate  the  articles  when  they  are 
packed  away,  using  carbon  disulfid.  Thus  an  ordinary  trunk  filled  with 
such  articles  can  be  fumigated  for  from  24  to  48  hr.,  then  opened  and  a 
liberal  supply  of  moth  balls  (naphthaline)  or  flake  naphthaline  be  added 
and  the  trunk  finally  closed. 

Repellents  are  of  some  value  to  keep  clothes  moths  away  from 
materials  liable  to  injury,  but  their  value  is  largely  dependent  upon  the 
amount  used  and  on  whether  the  insects  are  already  present.  It  appears 
that  while  clothes  moths  will  not  usually,  at  least,  lay  their  eggs  on 
materials  stored  with  an  abundant  supply  of  naphthaline,  this  substance 


238  APPLIED  ENTOMOLOGY 

in  any  such  amounts  as  are  usually  added  will  not  keep  eggs  already 
present  from  hatching,  nor  the  larvae  from  feeding.  Therefore,  fumiga- 
tion first,  to  kill  any  of  these  insects  which  may  be  present  in  any  stage, 
followed  by  an  abundant  supply  of  naphthaline  to  keep  them  away 
thereafter  would  seem  to  be  the  best  method  of  procedure. 

Other  repellents  often  used  are  cedar-wood  chests,  sprigs  or  chips  of 
cedar,  camphor,  tarred  paper,  and  tobacco.  They  are  all  repellents, 
but  apparently  less  effective  than  naphthaline.  In  the  case  of  cedar  it 
is  the  oil  present  which  gives  the  protection,  and  as  this  is  volatile  it  is 
lost  after  a  time  and  then  a  cedar  chest  is  of  no  more  value  for  storage 
than  one  of  any  other  kind  of  wood. 

Closets  often  become  infested  by  clothes  moths  and  even  after  taking 
out  and  treating  the  clothing  the  moths  may  appear.  It  is  probable 
that  in  such  cases  the  larvae  find  particles  of  wool  or  other  edible  materials 
in  the  cracks  of  the  floor  or  e^e where  on  which  to  live.  In  such  cases  the 
free  use  of  gasoline  or  kerosene  on  the  walls  and  floors,  paying  particular 
attention  to  all  cracks,  followed  after  a  few  hours  by  a  thorough  airing, 
should  give  relief.  If  not,  fumigation  of  the  closet,  being  careful  that 
cracks  around  the  doors  or  other  openings  are  tightly  sealed,  will 
exterminate  the  insects  there. 

Rugs  and  carpets  infested  should  be  thoroughly  cleaned  and  can 
then  either  be  baked  to  125°F..  fumigated  as  above,  or  sprayed  with 
benzine.  Furniture  attacked  may  be  saturated  with  benzine  or  fumi- 
gated. Where  an  entire  house  is  infested,  no  one  place  apparently 
more  than  another,  fumigating  with  hydrocyanic  acid  gas  at  the  rate 
of  1  oz.  of  sodium  cyanid  to  every  100  cu.  ft.  of  space  has  given  good 
results. 

Rugs,  furs  and  woolens  valuable  enough  to  place  in  cold  storage 
may  be  protected  during  the  summer  by  cold.  It  has  been  found  that 
exposing  infested  goods  to  very  low  temperatures  for  a  few  days,  followed 
by  another  short  period  in  a  fairly  warm  place,  then  returning  them  to  the 
cold  room  for  a  short  time  will  kill  the  insects  present,  these  being  unable 
to  live  through  such  severe  temperature  changes.  After  this  the  articles 
can  be  stored  during  the  rest  of  the  season  in  a  temperature  of  about  40°F. 
with  safety. 

Family  Eucosmidae. — In  this  family  are  a  number  of  pests  of  fruit 
trees  and  other  plants.  All  of  them  are  small  moths,  rarely  spreading 
over  three-quarters  of  an  inch.  One  of  the  worst  pests  of  the  apple — the 
apple-worm  or  codling  moth — belongs  here. 

The  Codling-moth  (Laspeyresia  pomonella  L.). — This  pest  of  apples, 
pears  and  occasionally  of  other  fruits  is  a  native  of  Southeastern  Europe 
but  is  newfound  almost  every  where  and  is  present  in  all  the  apple-growing 
sections  of  this  country. 


THE  LEPIDOPTERA 


239 


The  adult  moth  (Fig.  234)  has  its  fore-wings  brown,  crossed  by  irreg- 
ular gray  and  brown  lines.  It  spreads  about  three-quarters  of  an  inch 
and  is  not  often  seen  as  it  flies  only  at  night  and  is  not  attracted  by  lights. 

Winter  is  passed  in  the  full-grown  caterpillar  stage  in  some  protected 
place,  usually  under  a  piece  of  bark  of  the  tree  where  the  insect  fed  (Fig. 
235).     Under  the  bark  the  caterpillar  digs  out 
an  oval  cavity  and  lines  it  with  silk  in  which  to 
winter.     In  the  spring  it  pupates  here  and  the 
adult    moth   escapes   a  week  or  two  after  the 
petals   fall   at   the    blossoming    season    in    the 


IP^ 

; 


FIG.  234.  FIG.  235. 

FIG.  234. — Adult  Codling  Moth  (Laspeyresia  pomonella  L.),  twice  natural  size. 
(Original.) 

FIG.  235. — Piece  of  bark  showing  Codling  Moth  cocoons  and  pupae  on  its  under 
surface.  About  one-third  less  than  natural  size.  (Modified  from  Cornell  Agr.  Exp.  Sta. 
Bull.  142.) 

spring.  Tiny,  white,  flattened  eggs,  50  to  75  in  number,  are  now  laid 
singly  on  leaves,  twigs  or  on  the  small  fruit,  but  mainly  on  the  leaves. 
The  eggs  hatch  in  about  a  week  and  the  little  caterpillars  feed  for  a  short 
time  on  the  foliage,  but  soon  leave  this  and  crawl  to  the  fruit,  where  from 
60  to  80  per  cent  enter  at  the  blossom  end,  often  burrowing  their  way 
through  between  the  closed  calyx  lobes  or  sepals  to  reach  the  cup-shaped 
cavity  within.  From  the  bottom  of  this  cavity  they  tunnel  into  the  fruit 
to  the  core,  in  and  around  which  they 
feed  until  full-grown;  a  period  of 
nearly  a  month  in  most  cases.  The 
other  20  to  40  per  cent  enter  the  fruit 
at  any  point,  but  appear  to  prefer  a 
place  where  a  leaf  or  some  other 
object  lies  against  the  fruit. 

When  its  growth  has  been  com- 
pleted the  caterpillar  (Fig.  236)  is 
about  three-quarters  of  an  inch  long, 

pinkish  or  whitish,  with  its  head  and  a  patch  above,  just  behind  the  head, 
and  another  at  the  hinder  end  of  the  body,  brown.  It  now  leaves  the 
fruit,  generally  burrowing  out  through  the  side  and  makes  its  way  down 
the  tree  until  it  finds  some  piece  of  bark  loose  enough  to  permit  it  to 
gnaw  its  way  under,  and  'here  it  forms  an  oval  cavity  as  already 
described. 


FIG.  236.— Full-grown  larva  of  Codling 
Moth,  about  twice  natural  size.  (Modi- 
fied from  Cornell  Agr.  Exp.  Sta.  Bull.  142.) 


240  APPLIED  ENTOMOLOGY 

Over  the  greater  part  of  the  United  States  there  are  two  generations 
of  the  Codling-moth  each  year.  Where  this  is  the  case  the  larva  pupates 
in  this  cavity  for  about  2  weeks  before  it  escapes  as  an  adult.  Eggs  are 
now  laid  for  the  second  generation  and  on  hatching  the  larvae  attack  the 
fruit,  which  is  quite  well  grown  by  this  time,  entering  it  at  any  point  and 
showing  no  preference  for  the  blossom  end.  The  feeding  of  this  genera- 
tion of  caterpillars  proceeds  as  with  the  spring  generation,  but  in  many 
cases  has  not  been  completed  when  the  fruit  is  gathered.  In  this  way 
a  number  of  the  larvae  may  be  carried  to  the  bins  or  barrels  in  which  the 
fruit  is  stored.  Later,  they  leave  the  fruit  and  make  their  wintering 
cases  on  the  sides  of  the  bins  or  elsewhere. 

In  the  Northern  States  there  is  only  a  partial  second  generation, 
most  of  the  caterpillars  feeding  during  late  June  and  July,  failing  to 
transform  into  moths  that  season,  so  that  the  work  of  the  insects  in  fruit 
during  the  fall  is  comparatively  unimportant.  From  Southern  New 
England  south,  however,  two  complete  generations  are  the  rule  and  in  the 
more  southern  States  with  long  growing  seasons,  there  may  be  three  gener- 
ations. In  the  West,  even  as  far  north  as  Washington,  two  generations 
occur.  Cold  and  drought  have  a  considerable  effect  everywhere,  how- 
ever, late  springs  reducing  the  number  of  moths  which  appear  the  same 
season. 

The  injury  caused  by  this  insect  places  it  among  our  most  important 
pests.  Small  apples  attacked,  drop  in  many  cases,  resulting  in  the  entire 
loss  of  some  of  the  fruit  early  in  the  season.  In  years  of  an  abundant 
crop,  this  is  of  less  importance,  but  in  "off  years"  it  is  a  serious  matter. 
Fruit  infested  which  remains  upon  the  tree  is  reduced  in  value  and  thus 
another  loss  is  produced.  It  has  been  estimated  that  a  few  years  ago 
the  State  of  New  York  alone  lost  apples  and  pears  forming  a  third  of  the 
entire  crop,  which  valued  at  $1.50  per  barrel,  would  amount  to  about 
$3,000,000  per  year. 

Control. — There  appear  to  be  two  chief  ways  by  which  the  habits  of 
this  insect  aid  in  control  measures.  The  number  which  enter  the  fruit 
at  its  blossom  end  is  large,  and  poison  placed  there  for  them  to  eat  as  they 
bore  their  way  through  it  into  the  apple,  has  proved  effective.  The  fact 
that  the  caterpillars  feed  for  a  time  on  the  leaves  before  going  to  the  fruit 
also  indicates  a  place  for  successful  treatment. 

Accordingly,  spraying  with  arsenate  of  lead,  standard  formula,  within 
10  days  after  the  petals  fall,  directing  the  spray  so  that  as  far  as  possible 
it  will  fall  into  the  cup  surrounded  by  the  calyx  lobes  (sepals)  is  the  most 
usual  method  of  control.  In  applying  this  spray,  however,  it  should  be 
remembered  that  in  the  case  of  the  apple  these  calyx  lobes  which  at  first 
stand  widely  open  around  the  edges  of  the  cup,  soon  draw  together  and 
close  up  the  cup  mouth,  after  which  no  spray  can  be  placed  where  it  is  of 
use  (Fig.  237).  This  closing  comes  about  10  days  after  the  petals  fall 


THE  LEPIDOPTERA 


241 


(Fig.  238)  and  thus  limits  the  effective  spray  period  to  that  time.  For- 
tunately, different  varieties  of  apples  do  not  bloom  at  quite  the  same  time, 
so  that  spraying  where  large  orchards  are  involved  should  begin  with  those 


FIG.  237. — Apple   blossoms  in  proper  condition  for  receiving  the   calyx   spray.     Adult 
Codling  Moth,  natural  size,  above.     (From  Felt,  27th.  Rept.  N.  Y.  Slate  Ent.,  1911.) 

trees  which  lose  their  petals  first,  taking  the  later-blooming  varieties 
afterwards.  When  the  sepals  close  this  helps  to  hold  the  poison  in  the 
cup  ready  to  be  consumed  whenever  the  caterpillars  reach  it.  Where 


FIG.  238. — Small  apple  showing  calyx  lobes  practically  closed.     Too  late  for  successful 
spraying.     (Modified  from  Cornell  Agr.  Exp.  Sta.  Bull.  142.) 

pears  are  to  be  sprayed,  their  treatment  can  be  postponed  until  the  work 
on  the  apples  has  been  completed,  as  in  the  pear  the  calyx  lobes  do  not 

16 


242  APPLIED  ENTOMOLOGY 

close  and  the  spray  can  be  successfully  applied  more  than  10  days  after 
the  petals  fall. 

About  3  weeks  after  the  petals  have  fallen,  or  perhaps  a  few  days 
later,  a  second  spray  of  arsenate  of  lead,  placed  upon  the  leaves,  poisons 
these  just  before  the  young  caterpillars  of  the  Codling-moth  hatch  and 
begin  to  feed.  Many  of  these  larvae  will  thus  be  poisoned  before  they 
reach  the  fruit. 

Another  application  of  arsenate  of  lead  8  or  9  weeks  after  the  petals 
fall  will  poison  the  leaves  just  before  the  second  generation  of  caterpillars 
begins  feeding,  which  seems  to  be  the  chief  protection  available  against 
these  insects  at  this  time. 

Minor  methods  for  reducing  the  numbers  of  this  pest  are  also  made  use 
of.  Some  of  the  caterpillars  may  escape  death  from  feeding  on  the  poi- 
soned leaves  and  in  the  first,  as  well  as  in  the  second  generation,  enter  the 
fruit  through  the  side.  These  larvae  cannot  themselves  be  reached,  but 
the  pupse  or  adults  they  become,  if  destroyed,  will  reduce  the  number  of 
the  next  generation.  To  accomplish  this  all  loose  bark  on  the  trees  is 
removed  about  the  first  of  July  (earlier  in  the  South)  and  a  loose  band  of 
cloth  or  burlap  is  placed  around  the  trunk.  The  larvae  on  leaving  the 
fruit,  seek  for  a  place  in  which  to  transform  to  adults,  and  finding  no  bark 
under  which  to  make  their  cocoons,  crawl  down  the  tree  till  they  find  the 
band  which  provides  the  opportunity  they  desire,  and  under  which  they 
therefore  go.  Turning  over  this  band  frequently  during  the  summer  and 
fall  and  destroying  the  insects  found  under  it  will  therefore  eliminate 
them  from  any  further  consideration. 

Cleaning  out  bins,  barrels  and  all  other  places  where  fruit  has  been 
stored,  early  in  the  spring,  destroying  all  the  insects  found  there  is  also 
a  good  practice  and  is  a  desirable  treatment  for  the  Codling  moths 
located  in  such  places. 

In  spraying  for  the  codling-moth  there  has  been  a  considerable 
difference  of  opinion  as  to  the  most  successful  method.  Some  western 
workers  have  advised  a  rather  coarse  spray  driven  with  great  force,  such 
as  by  a  pressure  of  200  Ib.  or  more  at  the  pump,  just  after  the  petals 
fall,  claiming  that  in  this  way  the  spray  is  driven  to  the  bottom  of  the 
cup  and  that  later  sprayings  are  unnecessary.  Others,  mainly  in  the 
East,  have  advised  a  misty  spray  driven  by  a  pressure  of  about  100  Ib., 
and  giving  a  second  (and  where  there  are  two  full  generations  a  third) 
spray.  These  opposing  views  may  have  an  explanation  in  the  different 
conditions  in  apples  at  the  calyx  end  during  and  after  the  closing  of  the 
calyx  lobes  in  different  parts  of  the  country,  but  in  general  a  compromise 
between  the  two  methods,  resulting  in  the  use  of  a  medium  spray  driven 
with  considerable  force,  followed  by  the  other  sprays  as  they  may  be 
needed,  seems  to  be  the  usual  practice  at  the  present  time. 


THE  LEPIDOPTERA 


243 


Family  ^Egeriidae  (The  Clear-winged  Moths). — This  family,  some- 
times called. the  Sesiidse,  includes  a  number  of  moths  whose  wings  are 
only  partially  covered  by  scales.  They  are  not  large  insects,  spreading 
on  an  average,  about  an  inch  and  are  often  brilliantly  colored.  They 
fly  during  the  day  and  particularly  during  its  warmest  portion,  and  are 
very  rapid  in  their  flight.  The  larvse  are  whitish  in  color  and  are  all 
borers,  either  in  stems,  roots  or  under  bark.  They  are  therefore,  all 
injurious,  their  importance  to  man  depending  on  the  value  of  the  plant 
attacked. 

The  Peach  Borer  (Synanthedon  exitiosa  Say). — This  insect  which  is 
a  native  of  North  America  is  a  serious  pest  of  the  peach  wherever  these 
trees  occur  east  of  the  Rocky  Mountains.  West  of  this  a  very  closely 
related  species,  the  Pacific  Peach  Borer  (Synanthedon  opalescens  Hy. 
Edw.)  has  a  similar  life  history,  habits  and  control  methods. 


r 


FIG.  239. — Adult  Moths  of  the  Peach  Borer  (Synanthedon  exitiosa  Say),  twice  natural 
size:  a,  male;  &,  female.  (From  Britton,  Ninth  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1909:  after 
Beutenmuller.) 

The  adult  insect  (Fig.  239)  is  a  little  larger  than  the  average,  usually 
spreading  a  little  more  than  an  inch.  The  male  has  a  dark  blue  body 
and  its  transparent  wings  are  bordered  with  blue.  In  the  female  the 
fore  wings  are  entirely  blue,  the  hind  wings  .transparent  and  an  orange 
band  crosses  the  blue  body  at  about  the  middle  of  the  abdomen.  The 
moths  may  often  be  noticed  darting  about  in  peach  orchards  during  the 
middle  of  the  day,  anywhere  between  early  May  and  October  (even 
earlier  in  the  Gulf  States),  but  are  most  abundant  during  June  and  July 
in  the  Southern  States,  and  July  and  August  in  the  North.  The  eggs, 
several  hundred  in  number,  are  laid  singly  or  a  few  together  on  the  trunk 
of  the  tree  near  the  ground,  and  the  larvse  on  hatching  bore  into  the 
sap-wood  close  to  the  ground  and  feed  in  that  region  until  winter,  at 
which  time  most  of  them  are  about  one-third  grown.  In  the  spring  they 
resume  their  feeding  (Fig.  240)  and  upon  reaching  full  size  work  their 
way  to  the  surface  and  pupate,  forming  their  cocoons  of  their  excrement 


244 


APPLIED  ENTOMOLOGY 


and  particles  of  bark,  and  lined  with  silk.  These  cocoons  may  be  at  the 
openings  of  the  burrows  but  are  more  frequently  fastened  to  the  bark 
just  about  at  the  level  of  the  ground.  After  3  to  4  weeks  in  the  pupa 
stage,  the  transformation  to  the  adult  is  completed  and  the  pupa  breaks 

its  way  through  the  cocoon  until  it  is 
about  halfway  out.  Then  the  pupa  skin 
splits  and  liberates  the  moth. 

The  injury  caused  by  this  insect  when 
it  is  abundant  is  often  serious.  The  feeding 
of  the  borers  is  in  the  cambium  layer  which 
is  tunneled  through  in  an  irregular  way, 
interfering  with  the  growth  of  the  trees, 
and  where  these  are  small  they  are  often 
girdled.  The  weakened  trees  also  become 
more  liable  to  injury  and  destruction  by 
bark  borers  and  other  insects. 

Where  the  tunnels  are  formed,  a  flow  of 
sap  results  in  the  pouring  out  of  gum  and 
this  substance  on  the  bark  near  the  ground 
is  usually  a  good  indication  of  the  presence 
of  the  borers. 

Control. — Of  the  many  methods  which 
have  been  tried,  only  two  appear  to  have 
given  at  all  valuable  results.  These 
are  " worming"  and  " mounding."  Worm- 
ing is  the  removal  of  the  borers  late  in  the 
fall  and  again  in  the  spring,  the  date  for 
the  spring  treatment  varying  with  the 
locality  but  before  the  borers  have  com- 
pleted their  feeding.  A  day  or  two  before 
this  treatment  the  earth  around  the  trunk 
should  be  removed  to  a  depth  of  several 
inches,  so  that  fresh  gum  and  sawdust  pro- 
duced thereafter  by  the  borers,  or  below 
the  level  of  the  ground,  will  show.  With 
these  as  guides  where  to  work,  the  borers 
can  be  located  and  removed  with  a  sharp 
knife,  and  a  light,  pointed  wire,  care  being 
taken  to  cut  as  little  as  possible  and  to 

leave  clean-cut  edges.  Then  replace  the  earth.  In  the  spring,  following 
the  "  worming,"  mound  up  the  earth  six  or  eight  inches  high  around 
the  trunk  and  leave  it  there  until  after  the  moths  are  done  flying,  but 
remove  it  in  time  for  the  bark  to  harden  before  winter.  This  mounding 
forces  the  moth  to  lay  its  eggs  further  up  where  the  bark  is  tough 


FIG.  240.— Larva  of  Peach  Borer 
Moth  and  its  work  on  a  young 

peach  tree.     (From    U,  S.  D.  A. 

Farm.  Butt.  908.) 


THE  LEPIDOPTERA 


245 


and  harder  than  at  and  below  the  ground  level,  and  fewer  of  the  borers 
are  able  to  penetrate  it  to  the  cambium  layer. 

Probably  more  kinds  of  materials  have  been  tested  for  the  control 
of  this  insect  than  of  any  other,  but  it  is  still  without  an  entirely  satis- 
factory treatment,  though  Paradichlorobenzine  pulverized  to  the  fineness 
of  coarse  salt,  has  given  fair  success  recently.  The  ground  close  to  the 
tree  is  somewhat  loosened,  an  inch  or  two  deep;  the  material  is  then 
evenly  sprinkled  around  the  trunk  in  a  band  an  inch  or  two  wide;  then 
two  or  three  shovels  of  earth  are  placed  over  it  and  compacted  with 
the  back  of  the  shovel.  Three-fourths  of  an  ounce  to  an  ounce  of  the 
material  is  enough  for  trees  6  to  15  years  old.  It  is  not  entirely  safe 
for  use  with  younger  trees.  The  base  of  a  tree  treated  thus,  should  be 
uncovered  a  month  or  so  later  and  left  exposed  for  a  day  or  two  before 
recovering  with  the  earth. 


FIG.  241. — Squash- vine  Borer  (Mellitia  satyriniformis  Hbn.) ;  a,  male  moth;  b,  female, 
wings  folded ;  c,  eggs  on  a  piece  of  squash  stem ;  d,  full-grown  larva  in  squash  stem ;  e,  pupa ; 
/,  pupal  case,  found  in  the  ground.  All  one-third  larger  than  natural  size.  (From  U.  S. 
D.  A.  Farm.  Bull.  856.) 


The  Squash-vine  Borer  (Melittia  satyriniformis  Hbn.). — This  pest  is 
also  a  native  of  the  New  World,  and  is  found  from  Canada  southward  to 
Brazil  and  west  practically  to  the  Rocky  Mountains.  It  attacks  the 
squash,  pumpkin  and  occasionally  the  gourd,  melon  and  cucumber,  but 
does  not  usually,  at  least,  infest  the  last  two  plants  when  the  others  are 
at  hand.  The  adult  moth  (Fig.  241  a  and  6)  is  about  the  same  size  as, 
but  a  little  stouter  than  the  Peach  Borer.  Its  fore  wings  are  a  dark, 
metallic  green,  its  hind  wings  transparent,  its  abdomen  orange  and  black 
and  its  hind  legs  heavily  fringed  with  long,  black,  orange  and  a  few  white 
hairs,  making  these  legs  look  very  large.  It  appears  about  the  time  the 
plants  are  large  enough  for  egg-laying  and  feeding  upon — in  April  or 
May  in  the  South;  in  June  in  the  Middle  Atlantic  States  and  in  July  in 
New  England — and  lays  its  eggs  at  first  near  the  base  of  the  plant  on  the 


246  APPLIED  ENTOMOLOGY 

stem  but  later  almost  anywhere  on  it.  About  200  eggs  (Fig.  24  Ic) 
are  laid  singly,  and  these  hatch  in  from  1  to  2  weeks.  The  larvae 
now  bore  into  the  stem  and  feed,  generally  working  toward  the  base  of 
the  plant,  making  holes  through  it  to  the  outside  here  and  there,  through 
which  some  of  the  excrement  is  expelled.  They  become  full-grown  (Fig. 
24 Id)  in  about  4  weeks  and  then  go  a  few  inches  into  the  ground  to 
pupate,  making  dark-colored  silken  cocoons  (Fig.  24 1/)  mixed  with  dirt. 
Some  soon  pupate  (Fig.  24 le)  while  others  remain  as  larvae  in  their 
cocoons  until  the  following  spring.  After  the  pupal  stage  has  been 
completed  the  pupa  works  through  the  cocoon  and  to  the  surface  of  the 
ground  and  the  moth  then  emerges  from  its  pupal  skin. 

In  the  South  there  are  two  generations  a  year  of  this  insect:  far- 
ther north  there  is  a  partial  second  generation,  and  in  the  northern 
part  of  its  range  there  is  only  one,  winter  in  any  case  being  passed  in  the 
ground. 

The  injury  caused  by  these  insects  when  they  are  abundant  is  serious. 
The  burrows  become  wet  and  slimy,  hastening  decay  and  thus  separating 
much  of  the  plant  from  its  roots.  The  feeding  also  interferes  with  the 
circulation  of  the  sap  to  some  extent.  A  sudden  wilting  of  the  leaves  is 
generally  an  indication  of  the  presence  of  the  borers,  and  coarse  yellowish 
excrement  beneath  the  stems  is  also  evidence  of  their  activity.  In  some 
cases  entire  fields  of  the  plants  have  been  killed  by  the  work  of  this 
pest. 

Control. — Sprays  tried  thus  far  have  proved  ineffective.  As  the 
winter  is  spent  in  the  ground  of  the  field  where  the  insects  fed,  it  is  evi- 
dent that  their  food  plants  should  not  be  planted  2  years  in  succession 
on  the  same  land.  Light  harrowing  of  infested  fields  in  the  fall  to  bring 
up  the  cocoons  and  expose  them  to  winter  surface  conditions,  followed 
by  spring  plowing  to  a  depth  of  at  least  six  inches  has  given  good  results. 
Planting  a  few  plants  of  very  early  varieties  of  summer  squash  as  a  trap 
crop  on  which  the  insects  may  lay  their  eggs  before  the  real  crop  is 
available  for  them,  followed  by  the  destruction  of  the  trap  plants  before 
the  larvae  are  full-grown  is  helpful.  Covering  the  stems  with  earth  to 
induce  the  production  of  roots  from  the  nodes  along  the  stem  will  often 
enable  an  attacked  plant  to  continue  to  grow  even  after  its  connection 
with  its  original  roots  has  been  destroyed.  Finally,  when  borers  are 
found  in  the  stems  they  may  be  cut  out,  using  a  sharp  knife  and  splitting 
the  stem  lengthwise  where  the  borer  is  and  removing  it,  then  covering 
the  stem  thus  treated  with  moist  earth  to  aid  it  in  healing  the  wound. 

Many  other  injurious  insects  belong  in  this  family,  among  which  the 
Imported  Currant  Borer  boring  in  currant  stems  and  killing  them;  the 
Blackberry  Crown  Borer  which  bores  in  the  roots  and  crown  of  the  black- 
berry and  raspberry  and  has  a  2-year  life  history;  and  the  Maple  Sesian 
which  bores  in  the  trunks  of  maples,  may  be  mentioned. 


THE  LEPIDOPTERA 


247 


FIG.  242. — Angoumois  Grain  Moth 
(Sitotroga  cerealella  Oliv.) :  a,  adult 
moth,  about  twice  natural  size;  b,  larva 
in  a  grain  of  wheat;  c,  pupa  in  another 
grain,  b  and  c  about  three  times 
natural  size.  (Modified  from  Sander.) 


Family  Gelechiidae. — Some  of  the  small  insects  which  compose  this 
group  are  leaf -miners;  others  feed  on  buds  and  others  skeletonize  leaves 
or  attack  plants  in  various  ways.  Many  are  injurious  at  times,  the 
amount  of  injury  done  depending  on  their  abundance  which  varies  from 
year  to  year. 

The  Angoumois  Grain  Moth  (Sitotroga  cerealella  Oliv.). — This  little 
insect,  a  native  of  Europe  where  it  was  extremely  injurious  in  the  French 
province  of  Angoumois,  whence  its  name,  has  been  known  in  the  United 
States  since  about  1730  and  is  widely  distributed  but  is  not  often  im- 
portant in  the  more  northerly  states.  The  larva  attacks  wheat,  barley, 
oats  and  corn,  both  in  the  fields  and 
in  storage,  often  destroying  a  large 
part  of  the  grain. 

The  adult  moth  (Fig.  242a)  is 
small,  spreading  about  half  an  inch, 
yellowish  in  color,  slightly  speckled 
with  black.  Winter  is  spent  as  the 
caterpillar  in  the  grain  wherever  it 
may  be  stored,  and  pupation  occurs  in 
the  spring,  also  in  the  grain,  followed 
by  the  emergence  of  the  adult  which 
flies  to  the  fields  and  lays  its  eggs, 
about  a  hundred  in  all,  in  the  young 

grain  heads.  The  eggs  hatch  in  about  a  week  and  each  tiny  caterpillar 
attacks  a  kernel,  gnawing  into  it  (Fig.  2426)  and  consuming  its  contents. 
After  about  3  weeks  the  larva  becomes  full-grown  and  pupates  in  the 
kernel  (Fig.  242c)  where  it  fed,  escaping  a  little  later  as  the  adult  moth. 
Eggs  are  now  laid  on  grain  ready  to  harvest  and  either  in  the  harvested 
grain  or  in  corn  after  it  has  been  husked  and  is  therefore  accessible  to 
the  insects,  there  now  follow  later  generations,  until  cold  stops  their 
further  development  which  is  resumed  the  following  spring. 

Small  grains  and  corn  thus  attacked  are  badly  injured,  not  only  by  con- 
sumption of  the  contents  of  the  kernels  but  also  because  of  the  presence 
of  the  bodies  of  the  insects  themselves  and  of  their  excrement  which 
/gives  a  disagreeable  taste  to  the  flour,  which  lacks  adhesiveness  and 
breaks  up  when  stirred  in  water. 

Control. — When  this  insect  is  present,  destroy  or  feed  all  waste  grain 
and  screenings  and  clean  up  all  grain  and  refuse  from  places  where  grain 
has  been  stored,  in  early  spring.  Good  grain  should  be  fumigated  at  this 
time  also,  if  the  caterpillars  are  present.  The  purpose  of  this  is  to  destroy 
the  insects  before  they  pass  to  the  growing  food  plants  out  of  doors. 
Threshing  the  grain  soon  after  harvest,  not  keeping  it  in  the  mow  long, 
is  also  important.  Fumigation  of  the  threshed  grain  for  24  hr.,  with 
Carbon  disulfid,  using  1  Ib.  for  each  100  bu.,  if  it  is  infested  or  heats, 


248 


APPLIED  ENTOMOLOGY' 


which  is  due  to  infestation,  is  an  important  control  which  should  not  be 
omitted.  If  the  insect  is  present  the  sooner  fumigation  is  given  the 
sooner  the  loss  by  feeding  will  be  stopped. 

Family  Pterophoridae. — The  insects  of  this  family,  though  rather  small,  are  of 
much  interest,  the  wings  being  cleft  for  a  part  of  the  distance  in  from  the  outer 
margin  toward  the  base  (Fig.  243).  In  most  cases  the  fore  wing  is  divided  into 
two  such  parts  and  the  hind  wing  into  three.  A  single  species  found  in  this 
country  and  placed  in  a  separate  family  (Orneodidse,  Fig.  244),  has  each  of  its 
wings  divided  into  six  parts. 


FIG.  243.  FIG.  244. 

FIG.  243. — Adult  Pterophorid  Moth  showing  the  cleft  wings,  nearly  twice  natural  size. 
(Original.) 

FIG.  244. — Orneodid  Moth  showing  the  cleft  wings.     Twice  natural  size.      (Original.) 

Most  of  the  Pterophoridse  are  not  of  great  economic  importance.  One  species, 
however,  causes  some  injury  to  the  grape  by  webbing  together  the  leaves,  usually 
the  terminal  ones,  and  feeding  within  the  web.  As  this  frequently  involves  a 
cluster  of  buds  which  may  also  be  fed  upon,  the  crop  may  be  somewhat  reduced 
in  this  way.  The  only  control  known  is  to  remove  the  webs  by  hand  and  crush 
the  little  caterpillars. 


FIG.  245. — Adult  Mediterranean  Flour  Moth  (Ephestia  kuhniella  Zell.),  three  times 
natural  size.  (From  Herrick's  Insects  Injurious  to  the  Household.  By  Permission  of  the 
Macmillan  Company,  Publishers.) 

Family  Pyralidae. — This  is  a  large  family  but  most  of  the  moths  belonging  here 
are  small.  The  members  of  the  group  have  very  varied  habits.  Some  fold  or  roll 
leaves ;  some  bore  in  plant  stems ;  some  feed  on  stored  cereals  or  dried  fruit ;  one  or 
two  feed  on  wax  and  are  pests  in  bee  hives ;  others  attack  foliage,  grass  or  vari- 
ous materials.  Many  are  injurious  but  few  can  be  rated  as  serious  pests  over 
the  entire  country. 


THE  LEPIDOPTERA  249 

The  little  white  or  brown  and  white  moths  which  are  so  numerous  in  grass 
fields  during  the  summer  months,  belong  here.  On  alighting  on  a  grass  stalk 
they  place  their  bodies  parallel  to  the  stems  and  fold  their  wings  closely  about 
them.  Their  larvae  feed  on  grass  and  are  sometimes  quite  injurious,  corn  and 
oats  suffering  severely.  Early  fall  plowing  and  replowing  early  the  following 
spring  are  helpful  under  such  conditions. 

Three  species  are  often  found  in  houses  attacking  flour,  meal,  cereals  and 
dried  fruits.  One  species,  the  Mediterranean  Flour  Moth  (Fig.  245)  (Ephestia 
kuhniella  Zell.)  spins  a  web  which  causes  flour  to  stick  in  loose  masses,  and  in  mills 
and  storage  houses  this  becomes  serious.  The  other  two  species  are  more  liable 
to  be  found  in  dried  seeds,  fruits,  etc.,  and  often  cause  considerable  injury.  In 
storage  houses  and  mills  fumigation  with  Hydrocyanic  acid  gas  is  often  used  as  a 
control,  and  if  the  place  can  be  heated  to  125°  F.  for  about  6  hr.,  this  also  has 
proved  effective. 

The  Bee  Moth  (Galleria  mellonella  L.)  also  belongs  here  (Fig.  246).  It  is  an 
enemy  of  the  bee-keeper  living  in  the  bee  hives  where  it  feeds  on  wax  and  spoils 
the  honey.  Strong  colonies  of  bees  can  usually  protect  themselves  from  this 


FIG.  246.  FIG.  247. 

FIG.  246. — Adult  Bee  Moth  (Galleria  mellonella  L.),  natural  size.      (Original.) 
FIG.  247. — Cocoons   of   the    Bee   Moth    from    the    inside   of   a   hive.     Natural   size. 
(Original.) 

pest,  particularly  the  Italian  races.  Where  necessary,  the  bees  can  be  transferred 
to  another  hive  and  the  infested  one  fumigated  with  Carbon  disulfid  (Fig.  247). 

The  European  Corn  Borer  (Pyrausta  nubilalis  Hbn.). — This  pest  of  corn  and 
many  other  plants  has  only  recently  been  discovered  in  this  country,  and  in  1920 
was  found  only  in  parts  of  New  Hampshire,  Massachusetts,  New  York, 
Pennsylvania  and  Ontario.  It  is  a  borer  in  plant  stems,  in  which  it  winters  as 
a  partly  grown  larva  (Fig.  248),  finishing  its  feeding  and  pupating  (Fig.  249)  in 
its  burrow  in  the  spring.  The  moths  appear  in  June  and  lay  300  or  400  eggs  in 
small  clusters  on  the  leaves  of  their  food  plants  and  the  larvae  tunnel  in  the  stems 
(Fig.  250),  becoming  full-grown  in  about  6  weeks  and  the  moths  these  produce 
appear  in  July.  Eggs  for  another  generation  are  now  laid  and  the  larvae  feed 
until  winter,  when  they  hibernate  in  their  burrows.  In  some  places,  instead 
of  two  generations  each  year  there  is  only  one. 

The  moths  spread  from  about  an  inch  to  an  inch  and  a  quarter.  The  male  is 
rather  dull  purplish  or  reddish-brown  with  yellow  spots  or  a  band  on  the  fore 
wings  and  grayish  hind  wings.  The  female  has  dull  yellow  fore  wings  more  or 
less  marked  with  brown,  and  grayish-brown  hind  wings.  The  moths  fly  most 
freely  about  dusk  and  are  only  slightly  attracted  to  lights. 


250 


APPLIED  ENTOMOLOGY 


Corn,  and  particularly  sweet  corn,  appears  to  be  a  favorite  food  of  this  insect, 
and  where  it  is  abundant  a  large  part  of  the  crop  may  be  destroyed.  Large- 
stemmed  weeds  such  as  barnyard  grass,  pigweed,  etc.,  are  also  attacked,  as  well  as 
dahlias,  gladiolus  and  other  cultivated  plants,  which  complicates  the  problem  of 
control. 

Control. — The  best  method  for  checking  the  ravages  of  this  pest  is  the  destruc- 
tion of  all  corn  stalks  to  below  the  ground  level,  either  by  burning  during  the 
winter  or  by  using  as  ensilage. 


FIG.  248.  FIG.  249.  FIG.  250. 

FIG.  248. — Part  of  a  corn  plant  showing  effect  on  the  tassels  of  the  work  of  the  Euro- 
pean Corn  Borer  (Pyrausta  nubilalis  Hbn.).  (From  a  drawing  by  Snodgrass,  U.  S.  D.  A. 
Bur.  Ent.) 

FIG.  249. — Corn  stalk  split,  showing  the  larvae  of  the  European  Corn  Borer  and 
their  tunnels.  About  natural  size. 

FIG.  250. — Corn  stalk  cut  into  to  show  the  pupa  of  the  European  Corn  Borer. 
Slightly  enlarged.  (Both  figures  from  drawings  by  Snodgrass,  U.  S.  D.  A.  Bur.  Ent.) 

Family  Limacodidae  (Slug  Caterpillars) . — The  insects  belonging  to  this  family 
are  of  little  importance  from  an  economic  standpoint,  but  their  larvae  are  curious 
in  appearance,  having  little  resemblance  to  ordinary  caterpillars.  Instead,  they 
are  slug-like,  short  and  rather  stout,  quite  flat  beneath,  and  appear  to  slide 
along  rather  than  crawl.  Many  have  spines  and  rather  showy,  colored  markings, 
in  some  cases  with  soft,  fleshy  projections  sometimes  partly  or  entirely  covered 
with  hairs.  The  Oriental  Moth  (Cnidocampa  flavescens  Walk.)  several  times 
imported  into  this  country  from  Asia  by  accident,. has  established  itself  in  Eastern 
Massachusetts  but  is  not  apparently  of  much  importance,  though  the  spines  on 
the  caterpillar  cause  a  nettling  of  the  skin  of  a  person  where  the  insect  has  been 
touched. 

Family  Psychidae  (Bag  Worms) . — The  caterpillars  of  a  few  species  of  moths 
in  this  country  construct  silken  bags  around  their  bodies,  partly  covered  with 


THE  LEPIDOPTERA 


251 


FIG.  251. — Common  Bag  Worm  (Thyridopteryx  ephemeroeformis  Haw.):  10,  bag,  as 
seen  in  winter;  11,  same,  cut  open,  showing  pupa  case  and  eggs;  12,  eggs;  13,  young  larva; 
14,  cases  of  young  larvae  on  a  twig;  15,  older  larvae  in  tbeir  bags,  one  hanging  by  a  thread 
it  has  spun;  16,  full-grown  larva  removed  from  its  case;  17,  full-grown  larva,  crawling; 
19,  adult  (wingless)  female  Moth;  20,  adult  male  Moth;  22,  bag  of  male  with  empty  pupa 
case  protruding  from  its  lower  end.  All  natural  size  except  12  and  13  which  are  greatly 
enlarged.  (From  Houser,  Ohio  Agr.  Exp.  Sta.  Bull.  332:  After  Felt.) 


252 


APPLIED  ENTOMOLOGY 


twigs  or  other  parts  of  the  plant  on  which  they  feed.  The  female  is  wingless  and 
lays  its  eggs  within  the  pupa  case  or  skin  she  vacated  on  becoming  adult.  Only 
one  species,  the  Common  Bag-worm  (Thyridopteryx  ephemerceformis  Haw.)  is  of 

much  importance,  but  where  this  is  plentiful 
the  plants  on  which  it  feeds  may  suffer  con- 
siderably (Fig.  251).  It  occurs  from  Massa- 
chusetts west  to  Nebraska  and  south  to  North 
Carolina,  Tennessee  and  Texas.  Spraying  in- 
fested trees  as  soon  as  the  eggs  hatch  in  the 
spring,  with  arsenate  of  lead,  standard  formula, 
is  usually  a  sufficient  control  without  a  second 
application  later. 

Family  Geometridae  (Inch  worms, 
Span  worms  or  Measuring  worms).  —  This 
is  a  large  family  in  this  country  and  the 
moths  vary  greatly  in  size,  some  being 
very  small  while  others  may  spread  nearly 
two  and  one-half  inches.  They  nearly  all 
have  rather  delicate  wings  and  are  fragile 
creatures. 

The  larvae  (Fig.  252)  have  a  peculiar 
appearance  when  moving,  as  the  feet  which 
are  usually  present  near  the  middle  of  the 
body  in  most  caterpillars,  are  lacking  in 
this  group,  leaving  only  the  three  regular 
pairs  near  the  front  end  and  two  pairs  at 
the  hinder  end.  In  consequence,  walking 
is  accomplished  by  bringing  the  hinder 
end  up  as  closely  as  possible  to  the  front 
end,  the  body  forming  at  this  time  a  loop. 
Then  the  front  legs  let  go  their  hold  and 
the  body  is  straightened  out  to  find  a 
place  where  the  front  legs  can  grasp  and 
hold  on.  This  striking  method  of  locomo- 
tion has  led  to  the  common  names  given 
FIG.  252.—  Two  "inch  Worm"  to  the  caterpillars  in  this  family. 

uppr'  ot  LT^O™  fikf:  .  Another  feature  of  ^erest  about  these 
twig.  Compare  with  real  twig  just  larvae  is  that  many  of  them  are  colored  and 

formed   so  as  to  ™ble          *-     When 


disturbed  the  caterpillar  releases  the  grasp 
of  its  front  feet  and  straightens  out,  standing  at  an  oblique  angle  to  the 
twig  it  is  holding  on  to,  and  resembles  a  dead  twig  of  the  plant.  Some 
have  markings  which  make  them  resemble  twigs  having  buds,  leaf  -scars 
or  scales  of  the  bark,  thus  increasing  their  deceptive  similarity. 


THE  LEPIDOPTERA 


253 


The  food  plants  of  the  insects  in  this  family  are  very  numerous. 
Trees  and  shrubs  of  many  kinds  including  fruit  trees,  currant  and  goose- 
berry bushes,  cranberries  and  other  plants  of  value  to  man,  suffer  from 
the  attacks  of  these  insects,  though  few  are  regularly  injured,  the  pests 
in  most  cases  being  destructive  only  for  a  year  or  two,  then  disappearing, 
at  least  for  the  most  part,  during  quite  a  period. 

Canker  Worms. — There  are  two  species  of  Geometers  which  are 
widely  distributed  over  this  country  and  which  at  times  do  serious  damage 
to  fruit  and  shade  trees.  They  are  known  as  Canker  Worms,  and  while 
they  differ  in  certain  features,  have  much  in  common.  In  both  species 
the  pupal  stage  is  passed  in  the  ground:  in  both,  the  female  is  wingless: 
in  both,  the  eggs  are  laid  on  the  twigs  of  the  trees,  and  in  both  the  cater- 
pillars feed  at  about  the  same  time  in  the  spring. 

The  Fall  Canker  Worm  (Alsophila  pometaria  Harr.)  occurs  in  nearly 
all  parts  of  the  Northern  United  States  as  far  west  as  Wisconsin,  and 
south  at  least  through  the  Middle  Atlantic  States.  It  has  also  been  re- 


FIG.  253.  FIG.  254. 

FIG.  253. — Male  Fall  Canker  Worm  (Alsophila  pometaria  Harr.),  about  natural  size. 
(From  Britton,  Eighth  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1908.) 

FIG.  254. — Adult  Female  Fall  Canker  Worm  on  a  cluster  of  eggs.  About  2^2  times 
natural  size.  (From  Houser,  Ohio  Agr.  Exp.  Sta.  Bull.  332.) 

ported  from  Colorado  and  California.  The  adult  male  moth  (Fig.  253) 
spreads  about  an  inch  and  a  quarter,  its  wings  light  gray  with  faint 
markings.  The  female  (Fig.  254)  is  light  gray,  and  wingless.  The 
moths  usually  appear  late  in  the  fall,  escaping  from  their  pupae  in  the 
ground,  and  the  females  crawl  up  the  tree  trunks  to  the  twigs  where  they 
lay  their  eggs  (Fig.  254)  in  clusters.  These  eggs  hatch  the  following 
spring,  as  the  leaves  develop,  and  the  caterpillars  (Fig.  255)  feed  on  the 
foliage  until  full-grown  some  time  in  June  in  the  Northern  States,  and 
earlier  farther  south.  During  this  time  they  often  drop  from  the  leaves 


254 


APPLIED  ENTOMOLOGY 


some  distance,  spinning  a  thread  as  they  go,  and  up  which  they  return 
to  resume  their  feeding.  A  sudden  jar  of  an  infested  tree  will  cause 
great  numbers  to  drop  or  "spin  down"  several  feet  in  this  way.  When 
feeding  has  been  completed  the  larvae  enter  the  ground  and  pupate. a 
few  inches  below  the  surface  in  a  silken  cocoon,  from  which  the  moths 
escape  late  in  the  fall. 


FIG.  255. — Fall  Canker  Worm  caterpillars  feeding  on  Elm.     Natural  size. 
Eighth  Rept,  Ent.  Conn.  Agr,  Exp.  Sta.  1908.) 


(From  Britton, 


The  Spring  Canker  Worm  (Paleacrita  vernata  Peck). — The  adult 
male  of  this  species  averages  slightly  less  in  its  wing-spread  than  the 
Fall  Canker  Worm  and  its  wings  are  somewhat  lighter  in  color.  It 
occurs  throughout  the  Eastern  United  States  except  in  the  South  and  has 
also  been  taken  in  Texas  and  California.  It  is  particularly  injurious 
at  times  in  the  Mississippi  Valley.  This  pest  escapes  from  its  pupa  in 
the  ground,  as  the  adult,  very  early  in  the  spring,  and  the  females  crawl 
up  the  trees  on  which  they  lay  their  clusters  of  eggs,  frequently  under 


THE  LEPIDOPTERA  255 

loose  bark  or  in  crevices.  These  eggs  hatch  about  the  time  the  leaves 
open  and  the  larvae  feed  during  about  the  same  period  as  the  other  species, 
and  enter  the  ground  to  pupate  at  nearly  the  same  time.  This  insect 
also  has  the  habit  of  spinning  down  on  a  thread  when  disturbed. 

Control  of  Canker  Worms. — The  wingless  condition  of  the  females 
which  necessitates  their  crawling  up  the  trunks  of  the  trees  in  order 
to  reach  the  places  where  their  eggs  are  laid,  offers  an  opportunity 
for  control  by  banding  the  trunks,  in  the  fall  for  the  Fall  Canker  Worm, 
and  at  the  first  warm  days  after  winter  has  broken  (even  in  February 
in  New  England,  in  some  seasons)  for  the  spring  species,  either  with 
sticky  bands  which  the  insects  are  unable  to  cross,  or  with  loose  fluffy 
cotton  in  which  they  become  entangled.  Care  should  be  taken  to  keep 
the  bands  fresh  or  in  order  so  that  no  gaps  through  which  they  can  crawl, 
or  bridges  of  their  dead  bodies  over  which  they  can  cross,  are  formed. 
If  the  caterpillars  are  already  feeding  when  their  presence  is  discovered, 
spray  with  arsenate  of  lead,  standard  formula. 


FIG.  256. — Silk  Worm  (Bombyx  mori  L.) :  adult  moth  and  its  cocoon.     About  natural  size. 

(Original.') 


Family  Bombycidse  (True  Silk  Worms). — The  only  representative  of 
this  family  in  North  America  is  the  Silk  Worm  (Bombyx  mori  L.)  intro- 
duced many  years  ago  because  of  the  silk  obtained  from  its  cocoon. 
It  does  not  appear  to  have  established  itself  anywhere  in  this  country 
and  silk-raising  has  not  proved  profitable  here  because  of  the  cost  of 
the  labor  required,  as  compared  with  that  in  the  Orient. 

The  adult  moth  (Fig.  256)  spreads  about  an  inch  and  three-quarters 
and  is  creamy-white  in  color,  with  two  or  three  faint  lines  across  the  fore 
wings.  The  larvae  feed  on  the  leaves  of  the  mulberry  and  Osage  orange 
trees,  and  when  full-grown  leave  their  food  and  spin  their  cocoons  (Fig. 
256).  When  spinning  has  been  completed  these  are  gathered  and  the 
insects  within  are  killed  by  heat  or  fumigation.  Now  the  loose  silk  of  the 
outside  is  removed  and  the  cocoons  are  ready  to  market.  Nearly 
73,000,000  Ib.  of  raw  silk  were  produced  in  the  world  in  1918,  and  the 
importance  of  the  industry  is  enormous. 


256 


APPLIED  ENTOMOLOGY 


Family  Lasiocampidae  (The  Lasiocampids) . — This  small  family 
includes  several  species  which  are  common  and  at  times  quite  important 
pests.  The  moths  are  of  only  medium  size,  with  rather  stout  bodies, 
antennae  fringed  on  one  side  (pectinate)  and  with  a  large  shoulder  at 
the  base  of  the  hind  wing,  instead  of  a  frenulum.  The  larvae  feed  on 
the  leaves  of  trees. 

The  Apple-tree  Tent-caterpillar  (Malacosoma  americana  Fab.). — 
This  native  insect  is  at  times  a  pest  for  several  years  in  succession,  after 
which  it  practically  disappears  for  some  time.  It  is  found  almost  every- 
where from  Canada  to  Florida  and  west  to  the  Rocky  Mountains.  From 

there  to  the  Sierra  Nevada  Moun- 
tains another  species  having 
similar  habits  occurs,  while  on 
the  Pacific  Slope  several  others 
are  present. 

The  adult  moth  (Fig.  257)  is 
rather  stout,  with  a  re'ddish- 
brown  body  and  wings,  the  front 


FIG.  257.  FIG.  258. 

FIG.  257. — Adult  Apple-tree  Tent-caterpillar  (Malacosoma  americana  Fab.),  about 
natural  size.  (From  Sanderson,  Insects  Injurious  to  Farm,  Garden  and  Orchard;  after  Lowe,) 

FIG.  258. — Egg  belt  of  the  Apple-tree  Tent-caterpillar,  encircling  a  twig.  Natural 
size.  (From  Britton,  Thirteenth  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1913.) 


pair  of  which  have  two  whitish  lines  crossing  them.  The  male  spreads 
about  an  inch  and  a  quarter  and  the  female  about  half  an  inch  more. 
They  fly  at  night  and  do  not  feed  as  adults.  The  wild  cherry  and  apple 
appear  to  be  the  preferred  food  plants  of  the  caterpillar,  but  other  fruit 
and  shade-trees  are  sometimes  fed  upon. 

The  moths  appear  during  the  early  part  of  the  summer  and  lay  their 
eggs  (Fig.  258),  200  or  300  in  number,  in  belts  around  small  twigs,  one 
belt  probably  being  all  that  is  laid  by  one  insect.  These  belts  more 
or  less  completely  surround  the  twig,  and  after  depositing  a  belt,  the 
insect  covers  the  eggs  with  a  layer  of  a  brown,  sticky  substance,  beveled 


THE  LEPIDOPTERA 


257 


down  to  the  twig  at  each  end,  which  soon  hardens  and  glistens.  Within 
the  eggs  the  larvae  develop  and  are  ready  to  hatch  by  winter,  but  remain 
within  the  egg-shells  until  spring.  They  then  leave  the  eggs  and  may 
feed  first  on  the  material  covering  the  eggs,  but  soon  crawl  together  to 
some  near-by  fork  of  the  tree  and  there  spin  a  web  (Fig.  259)  in  which 
to  live.  From  this  they  go  out  during  the  day  to  feed,  spinning  a  thread 


FIG.  259. — Tent  of  the  Apple-tree  Tent-caterpillar,  about  half  natural  size.     (Original.) 

as  they  go,  perhaps  to  aid  them  in  finding  their  way  back.  As  they  grow 
the  tent  or  web  is  enlarged  by  the  addition  of  outer  layers  and  may  be 
nearly  a  foot  long  and  seven  or  eight  inches  across  before  the  larvae  are 
full-grown,  the  feeding  period  being  about  6  weeks. 

Though  at  first  very  small,  the  larvae  grow  rapidly  and  when  of  full  size 
are  about  two  inches  long,  black  with  a  white  stripe  along  the  middle  of 
the  back  and  a  row  of  pale-blue  spots  on  each  side,  with  a  velvety-black 
spot  in  front  of  each  blue  one  (Fig.  260).  Fine  yellowish  hairs  are  also 
present. 

When  about  through  feeding  the  caterpillars  scatter  and  finally 
spin  rather  large,  quite  thick,  white  cocoons  in  any  protected  places 

17 


258 


APPLIED  ENTOMOLOGY 


they  may  find,  -and  within  these  they  pupate,  taking  about  3  weeks 
in  this  stage  before  the  moth  appears. 

An  unusual  feature  in  this  life  history  is  the  long  period  spent  in  the 
egg,  which  may  be  almost  10  months. 

Control. — Although  this  insect  has  numerous  enemies  both  among 
birds  and  insects,  there  are  periods  during  which  these  are  unable  to 
prevent  trees  being  stripped  by  the  pest.  In  general,  the  calyx  spray 
used  on  apples  and  pears  for  the  Codling  Moth  is  sufficient  to  destroy 


FIG.  260. — Larvae 


of     the    Apple-tree    Tent-caterpillar,    natural    size.     (From    Britton, 
Thirteenth  Rcpt.  Ent.  Conn.  Agr.  Exp.  Sta.  1913.) 


this  caterpillar  also.  On  wild  cherry  and  other  trees  not  usually  sprayed, 
however,  it  finds  a  breeding  place  from  which  the  fruit  trees  may  be 
restocked,  and  such  trees  should  also  be  cared  for,  to  prevent  this. 
Examination  of  such  trees  any  time  between  August  and  March,  to  find, 
cut  off,  and  burn  the  eggs,  and  the  destruction  of  the  caterpillars  while 
in  their  tents  on  rainy  days  or  at  night,  either  by  crushing  or  by  burning 
with  a  torch,  are  desirable  auxiliary  treatments  in  addition  to  spraying. 
The  torch  method  should  not  be  used  on  young  fruit  trees,  however,  as 
holding  the  torch  at  a  fork  a  moment  too  long  is  liable  to  injure  this 


THE  LEPIDOPTERA 


259 


place,  and  in  later  years  the  injury  will  show  as  the  fork  becomes  an 
important  one,  in  the  form  of  a  splitting  at  that  point  under  the  weight  of 
the  branches  and  fruit  beyond. 

The  Forest  Tent-caterpillar  (Malacosoma  disstria  Hbn.)  is  also  a 
native  of  North  America.  It  greatly  resembles  the  last  species,  both 
in  appearance  and  in  some  of  its  habits,  but  though  occasionally  found 
feeding  on  some  of  the  same  food-plants,  it  appears  to  prefer  the  oak, 
maple  and  other  forest  and  shade-trees. 

The  adult  (Fig.  261)  is  of  about  the  same  size  and  general  appearance 
as  the  Apple-tree  Tent-caterpillar,  but  the  general  color  is  lighter  brown 
and  the  lines  or  bands  across  the  fore  wings  are  darker,  instead  of  lighter 


FIG.  261.  'Fio.  262.  FIG.  263. 

FIG.  261. — Adult.  Forest  Tent-caterpillar    (Malacosoma  disstria  Hbn.),   natural  size. 

(Original.) 

FIG.  262. — Egg  belt  of  Forest  Tent-caterpillar,  natural  size.      (Original.) 

FIG.  263. — Full-grown  larva  of  the  Forest  Tent-caterpillar.     About  two-thirds  natural 

size.     (Original.) 

than  the  ground  color.  The  egg  belts  (Fig.  262)  are  similar  but  quite 
squarely  cut  off  at  their  ends  instead  of  being  rounded  down  to  the  twig: 
the  caterpillar  (Fig.  263)  has  a  row  of  rather  oval  white  spots  instead  of 
a  white  stripe  along  its  back,  and  its  sides  are  noticeably  light  blue, 
with  two  broken,  longitudinal,  yellow  lines.  The  caterpillars  make 
no  tents  but  scatter  after  hatching.  Otherwise  the  life  history,  time 
spent  in  the  different  stages  and  the  periods  of  the  year  during  which 
these  occur  are  the  same  in  both  species. 

Control. — Where  the  caterpillars  can  be  reached  by  sprays,  control  is 
comparatively  simple,  as  with  the  Apple-tree  Tent-caterpillar.  In 
forests,  however,  where  large  trees  are  stripped  of  their  foliage,  this 
method  is  rarely  practicable.  Destruction  of  the  egg-belts  is  of  value, 
but  these  can  seldom  be  reached  in  any  numbers,  being  usually  high  up 
on  the  small  twigs.  Jarring  the  trees  where  these  are  small  enough  for 
this,  will  cause  many  of  the  caterpillars  to  drop  to  the  ground,  and  by  the 
use  of  sticky  or  cotton  bands  they  may  be  prevented  from  crawling 
back  again.  The  caterpillars  frequently  cluster  in  large  numbers  on  the 
trunks  of  the  trees  and  at  such  times,  spraying  these  clusters  with  any 


260  APPLIED  ENTOMOLOGY 

strong  contact  insecticide  is  an  effective  treatment.  For  the  most  part, 
however,  little  can  be  done  and  in  "sugar  bushes"  extensive  defoliation 
with  a  consequent  reduction  of  the  vitality  of  the  tree  and  of  the  sap 
flow  will  follow,  only  relieved  after  a  year  or  two  by  an  increase  in 
the  enemies  of  this  insect  to  such  an  abundance  as  to  reduce  it  to 
unimportance. 

Some  of  the  western  species  of  Tent-caterpillars  make  tents,  while 
others  do  not.  Occasionally  one  species  or  another  may  become  so 
abundant  as  to  strip  everything  in  one  place,  and  in  such  cases  the  larvse 
crawl  off  in  enormous  numbers  seeking  for  more  food.  In  one  instance 
their  line  of  march  was  across  a  railroad,  where  they  were  crushed  by  the 
car  wheels  until  the  rails  became  so  slippery  that  trains  were  unable  to 
run  except  by  sweeping  the  caterpillars  off  or  by  blowing  them  off  the 
track  ahead  of  the  engine  by  jets  of  steam! 

Family  Lymantriidse  (The  Tussock  Moths). — This  family,  though 
small  in  numbers  in  this  country,  includes  some  serious  pests.  The 
moths  are  of  medium  size,  and  the  females  in  some  cases  are  either 
wingless  or  nearly  so.  The  legs  are  rather  thickly  clothed  with  hairs. 
The  group  as  a  whole  is  one  of  night-flying  insects  but  a  few  fly  freely 
in  the  day  time. 

The  larvse  are  often  highly,  even  brilliantly  colored,  and  are  thickly 
covered  with  hairs.  These  may  be  quite  uniformly  distributed,  but  in 
some  cases  there  are  also  bunches  or  "tussocks"  of  them  projecting  some 
distance  from  the  skin,  and  long,  slender  "pencils,"  composed  of  a  few 
hairs  which  may  be  a  quarter  as  long  as  the  body  of  the  caterpillar. 
Most  of  them  feed  on  the  foliage  of  trees  but  some  have  a  wide  range 
of  food  plants. 

The  White -marked  Tussock  Moth  (Hem,erocampa  leucostigma 
A.  &  S.). — This  common  species  is  found  along  the  entire  Atlantic  Coast 

from  Nova  Scotia  to  Florida  and  westward  at 
least  to  Nebraska,  and  has  also  been  reported 
from  Oregon.  It  is  mainly  a  pest  of  shade- 
trees,  and  most  injurious  in  and  near  cities 
and  towns,  but  at  times  attacks  fruit-trees  and 

oQiiQ^Q  TYTII o n   i n i n v\r 
FIG.  264.— Adult  male  of  injury. 

the  White-marked  Tussock          The  adult  male  moth  (Fig.  264)  spreads  about 

^ucoltigma  T^and^sT     an  inch>  and  its  win§S    are  6^  with  WaV^  dark 

about  natural  size.  (From  bands  and  light  marks.  Its  antennae  are  heavily 
Cmm* A  r^sta  190?)  ^^  fringed.  The  female  (Fig.  265)  is  wingless, 

with  a  gray  body. 

The  winter  is  spent  in  the  egg  stage,  the  larvse  hatching  in  the  spring, 
feeding  until  full-grown,  on  foliage,  then  crawling  away  to  pupate,  some- 
times on  the  twigs  but  usually  either  on  the  bark  of  the  trunk  or  lower 
limbs,  or  on  other  objects  near-by.  The  cocoons  are  composed  of  silk 


THE  LEPIDOPTERA 


261 


mixed  with  hairs  from  the  body  of  the  caterpillar  and  are  gray  in  color. 
The  female  on  emerging  from  the  pupa  stage  crawls  to  the  surface  of 
the  cocoon  and  later  lays  there  from  300  to  500  eggs  (Fig.  265)  which  she 
then  covers  with  a  white  froth  which  soon  hardens  and  forms  a  crust 
covering  and  hiding  the  eggs.  This  white  crust  on  the  gray  background 
of  the  cocoon  and  the  generally  dark  bark  of  the  tree  makes  the  eggs  very 
conspicuous  objects. 

The  eggs  soon  hatch  and  the  caterpillars  thus  produced  feed  on  the 
leaves  until  full-grown  (Fig.  266)  then  pupate  as  in  the  preceding  genera- 
tion and  the  moths  appearing  later,  also  lay  their  eggs  on  their  cocoons 
and  cover  them  with  white  froth.  It  is  probable  that  throughout  the 


FIG.  265.  FIG.  266. 

FIG.  265. — Adult  female  of  the  White-marked  Tussock  Moth  with  an  egg  mass  covered 
by  a  white  crust,  resting  on  her  cocoon.  About  natural  size.  (Modified  from  N.  Y.  Agr. 
Exp.  Sta.  Bull.  312.) 

FIG.  266. — Caterpillar  of  White-marked  Tussock  Moth.  Note  the  four  "tussocks"  of 
hairs.  Slightly  reduced.  (Modified  from  N.  Y.  Agr.  Exp.  Sta.  Bull.  312.) 

northern  part  of  the  territory  inhabited  by  this  insect,  these  eggs  will  be 
laid  so  late  in  the  season  that  they  will  not  hatch  until  the  following 
spring  and  the  white  crusts  covering  them  will  therefore  be  prominent 
objects  during  the  winter.  We  accordingly  find  two  generations  of  this 
insect  in  the  Middle  States;  one  in  the  North,  and  there  are  probably 
three  in  the  South,  corresponding  to  some  extent  at  least,  with  the 
length  of  time  during  which  food  is  available. 

The  moths  are  seldom  seen,  though  the  males  fly  somewhat  during 
the  day.  The  egg  clusters,  however,  are  objects  which  attract  attention 
and  the  caterpillars  are  highly  colored  and  so  peculiar  in  appearance  as 
to  be  very  noticeable.  A  full-grown  caterpillar  is  nearly  an  inch  and  a 
half  long,  with  a  bright  red  head  and  also  two  red  humps  above,  near  the 
hinder  end.  Between  the  head  and  the  middle  of  the  body  is  a  row  of 
four  large  cream-colored  tufts  or  " tussocks"  of  hairs  standing  up  some 
distance  above  the  surface  of  the  body.  The  side  is  grayish  with  a  yellow 
band  above  and  below.  Projecting  upward,  forward  and  outward  from 
just  behind  the  head  are  two  slender  clusters  of  black  hairs  or  "pencils" 


262  APPLIED  ENTOMOLOGY 

about  half  an  inch  long,  and  a  single  similar  but  gray  pencil  of  hairs 
projects  upward  and  backward  from  near  the  hinder  end  of  the  body. 
These  characters  make  the  caterpillar  of  this  insect  a  very  striking  and 
noticeable  animal. 

Control. — Gathering  and  destroying  the  egg  clusters  or  applying 
creosote  to  them  freely  enough  to  penetrate  the  crust  and  reach  all  the 
eggs  beneath  are  methods  which  can  be  made  use  of  whenever  the  clusters 
are  observed.  Spraying  for  the  caterpillars,  using  arsenate  of  lead, 
standard  formula,  is  also  effective.  Trees  not  infested,  whose  branches 
do  not  touch  those  of  other  and  infested  trees,  can  be  protected  by  the 
use  of  sticky  or  cotton  batting  bands  around  their  trunks  during  the 
periods  when  the  caterpillars  are  crawling. 

The  Antique  or  Rusty  Tussock  Moth  (Notolophus  antiqua  L.). — This 
is  a  European  insect  but  widely  distributed  in  North  America.  The 
male  moth  averages  about  as  large  as  the  White-marked  Tussock  Moth 
and  .has  rusty-brown  wings,  each  fore  wing  with  a  small  white  spot. 
The  female  is  wingless.  The  eggs  are  laid  on  the  cocoon  of  the  parent 
moth  but  without  any  white  crust  to  conceal  them,  and  the  caterpillar 
has  a  black  head.  Of  the  four  tussocks  on  the  back,  the  first  two  are 
black  at  first  but  become  whitish  later,  like  the  others.  The  pencils 
of  hairs  just  behind  the  head  and  at  the  end  of  the  abdomen  resemble 
those  of  the  other  species  and  an  additional  pair  is  also  present,  one  on 
each  side  of  the  body  a  short  distance  behind  the  head. 

The  life  history  of  this  insect  is  probably  similar  to  that  of  the  last 
species,  though  the  number  of  generations  in  different  parts  of  the  country 
does  not  appear  to  have  been  worked  out.  In  the  Northern  States  there 
is  one  each  year.  Control  measures  are  the  same  for  both  species. 

The  Gypsy  Moth  (Porthetria  dispar  L.). — This  European  insect  was  intro- 
duced into  this  country  near  Boston,  Mass.,  by  accident,  about  1869  and  has 
gradually  spread  until  it  now  covers  the  greater  part  of  the  New  England 
States.  It  has  also  appeared  in  other  localities  but  these  places  were  dis- 
covered early  and  the  insects  exterminated. 

The  adult  male  moth  (Fig.  267)  is  brown  with  some  yellowish  markings,  and 
spreads  about  an  inch  and  a  half.  It  flies  freely  during  the  day.  The  female 
has  nearly  white  wings,  with  dark  markings;  a  stout,  heavy  body  covered  behind 
with  buff  hairs:  its  wings  spread  about  two  inches,  and  though  having  well-de- 
veloped wings,  this  sex  does  not  fly. 

Winter  is  passed  in  the  egg  stage,  the  caterpillars  hatching  in  the  spring  and 
feeding  on  many  kinds  of  leaves,  though  the  apple,  oak,  willow,  alder  and  birch 
appear  to  be  favorites,  and  shrubs  and  herbaceous  plants  do  not  escape.  Ash 
is  not  fed  upon,  nor  is  pine  during  the  first  two  instars. 

Feeding  until  early  in  July  the  caterpillars  become  full-grown  (Fig.  268)  and 
may  then  be  nearly  three  inches  long  and  as  large  as  a  lead  pencil.  They  are 
brown,  partially  hairy,  the  hairs  being  somewhat  clustered,  and  on  the  back  bear 
five  pairs  of  blue  spots,  followed  behind  by  six  pairs  of  red  ones.  At  the  end  of 


THE  LEPIDOPTERA 


263 


the  feeding  period  the  caterpillar  crawls  to  any  satisfactory  place,  usually  the 
underside  of  some  limb  or  on  the  trunk,  and  there  spins  a  few  threads  to  hold  its 


FIG.  267. —  Adults  of  the  Gypsy  Moth  (Porthetria  dispar  L.) ;  female  on  left;  male  on  right. 
Natural  size.     (From  Britton,  Fifth  Kept.  Ent.  Conn.  Agr.  Exp.  Sta.  1905.) 

body  in  place  rather  than  for  concealment  or  protection,  and  in  this  exceedingly 
scanty  cocoon  it  pupates  (Fig.  268)  and  after  a  period  of  from  a  week  to  17  or 
18  days,  the  moth  emerges. 


FIG.  268. — Pupae  and  larvae  of  the  Gypsy  Moth,  natural  size.     (From  Britlon,  Fifth  Rept. 
Ent.  Conn.  Agr.  Exp.  Sta.  1905.) 

The  eggs  are  now  laid  in  oval  clusters  throughly  covered  by  buff  hairs  from 
the  abdomen  of  the  moth,  and  each  cluster  may  contain  from  four  to  five  hundred. 
There  seems  to  be  little  choice  where  the  clusters  are  placed,  many  being  on  the 


264  APPLIED  ENTOMOLOGY 

trunks  and  limbs  of  the  trees,  but  others  are  found  in  cavities  in  the  trunks,  on 
the  stones  of  stone  walls,  even  in  the  middle  of  the  wall,  in  tin  cans,  and  in  fact, 
anywhere  the  female  may  crawl  to.  They  hatch  the  following  spring. 

Distribution  appears  to  be  accomplished  by  the  crawling  of  the  caterpillars; 
by  carrying  to  other  places  objects  on  which  egg-clusters  have  been  deposited; 
by  caterpillars  spinning  down  on  threads  from  the  trees  onto  passing  vehicles; 
and  by  the  wind. 

The  injury  caused  by  this  insect  is  often  very  serious.  The  caterpillars 
have  voracious  appetites  and  eat  large  amounts  and  their  abundance  has  often 
resulted  in  the  stripping  of  large  areas,  which  repeated  several  years  in  succession 
usually  causes  the  death  of  the  trees.  With  evergreens,  a  single  defoliation  is 
usually  sufficient  to  kill  the  trees,  and  in  many  parts  of  Eastern  Massachusetts 
the  thinning  of  woodland  areas  in  consequence  of  the  work  of  these  insects,  is 
very  evident. 

Parasites  and  other  enemies  of  the  Gypsy  Moth  have  been  introduced  in 
large  numbers  by  the  Federal  Government,  and  where  these  have  become  abun- 
dant they  have  done  good  work,  though  of  course  nothing  like  extermination  of 
the  pest  has  been  accomplished.  A  wilt  disease  present  in  favorable  seasons, 
kills  many  of  the  larvae  at  such  times.  In  general  though,  outbreaks  of  this 
insect  in  any  locality  are  not  repressed  by  their  natural  enemies  for  several  years, 
and  in  the  meantime  the  damage  is  great.  This  condition  therefore  calls  for 
the  use  of  control  methods. 

Control. — The  egg  clusters  constitute  one  place  where  control  measures  can 
be  applied.  It  is  much  easier  to  kill  400  or  500  insects  concentrated  in  a  space 
an  inch  square  or  less,  than  the  same  number  in  the  larval  stage,  scattered  over 
a  tree.  Soaking  the  egg  clusters  at  any  time  after  they  are  laid  until  they  hatch 
the  following  spring,  with  creosote  to  which  a  little  lampblack  has  been  added 
(to  show  by  its  color  which  clusters  have  been  treated  and  which  have  not)  is  a 
good  treatment.  Care  must  be  taken,  however,  in  using  this  material,  to  take 
enough  to  reach  all  the  eggs  in  the  cluster.  Usually  a  swab  on  the  end  of  a 
stick,  soaked  in  the  creosote,  is  used  for  this  work.  The  difficulty  with  this 
method  is  that  of  finding  all  the  egg  clusters  in  their  varied  places  of  concealment. 

While  the  caterpillars  are  very  small,  spraying  infested  trees  and  other 
plants  with  arsenate  of  lead,  using  about  5  Ib.  of  the  paste  (2^  Ib.  of  the  powder) 
in  50  gal.  of  water,  is  a  good  treatment,  but  as  the  larvae  become  larger  they 
seem  to  develop  a  greater  resistance  to  poisons  and  spraying  becomes  less 
effective. 

As  the  larvae  feed  largely  at  night  and  seek  concealment  during  the  day,  put 
loose  bands  of  burlap  around  the  trunks  of  infested  trees,  where  they  may  hide 
in  the  daytime.  Success  with  this  method  of  control  is  dependent  upon  daily 
visits  to  the  bands  and  the  destruction  of  the  caterpillars  found  under  them. 

Sticky  bands  around  the  trunks  of  non-infested  trees  will  keep  the  caterpillars 
off  such  trees  as  long  as  the  bands  remain  fresh  and  in  good  order. 

As  the  caterpillars  do  not  feed  on  the  pine  until  after  they  have  passed  their 
second  instar,  pure  stands  of  pine  may  be  protected  by  removing  all  under- 
growth other  than  pine  and  banding  the  trees  as  above,  to  prevent  older  larvae 
from  crawling  to  them  from  places  outside  where  they  have  obtained  their  earlier 
food. 


THE  LEPIDOPTERA 


265 


The  Brown-tail  Moth  (Euproctis  chrysorrhcea  L.,  Fig.  269). — This  is  another 
European  pest  which  was  accidentally  introduced  into  this  country  near  Boston, 


FIG.  269. — Brown-tail  Moth  (Euproctis  chrysorrhcea  L.) :  2,  adult  male;  3,  adult  female 
moth;  4,  egg  cluster  on  leaf,  covered  with  hairs  from  body  of  parent;  5,  caterpillars  feeding. 
About  natural  size.  (From  U.  S.  D.  A.  Bur.  Ent.  Bull.  87.) 

reaching  there  about  1892.    Since  that  time  it  has  spread  as  far  as  Nova  Scotia 
and  New  Brunswick,  and  also  practically  covers  all  of  New  England. 

The  moths  are  white  except  for  the  abdomen  which  has  a  few  brown  hairs, 
and  the  tip  is  covered  by  a  tuft,  large  in  the  female,  of  golden  brown  hairs — 


266  APPLIED  ENTOMOLOGY 

the  character  which  has  given  this  insect  its  common  name.  The  moths  spread 
about  an  inch  and  both  sexes  are  strong  fliers,  appearing  early  in  July.  They 
are  somewhat  attracted  to  lights  but  in  most  cases  the  females  found  thus 
attracted,  appear  to  have  already  laid  their  eggs.  The  moths  lay  200  or  300 
eggs  in  a  cluster,  usually  on  the  leaves,  and  cover  them  with  brown  hairs  from 
the  tip  of  the  abdomen.  They  hatch  in  from  2  to  3  weeks  and  the  little  cater- 
pillars feed  on  the  foliage  in  company  during  the  early  fall,  leaving  the  veins,  and 
thus  skeletonizing  the  leaves.  Early  in  September  they  go  together  to  the  tip 
of  some  twig  and  there  spin  a  very  tough,  dense,  silvery  tent  incorporating 
some  of  the  leaves  in  it,  to  use  as  their  resting  place  for  the  winter.  The  size  and 
form  of  this  tent  will  vary  with  the  number  of  caterpillars  contributing  to  its 
formation,  but  it  is  usually  three  or  four  inches  long  and  an  inch  or  two  in 
diameter  at  its  widest  p  lace.  After  the  leaves  fall  these  tents  at  the  tips  of 
the  twigs  are  very  conspicuous  objects  during  the  winter.  At  the  time  of  the 
formation  of  the  tent  the  caterpillars  are  about  one-third  of  an  inch  long. 

In  the  spring  as  soon  as  the  leaf-buds  begin  to  open,  the  caterpillars  leave 
their  tents  and  scatter,  feeding  until  June  when  they  become  fully  grown  and 
are  about  an  inch  and  a  half  long,  brown,  slightly  mixed  with  orange,  fairly  well 
covered  with  fine  reddish-brown  hairs,  and  with  two  bright  red  tubercles,  one 
behind  the  other,  on  the  middle  line  of  the  body  above,  near  the  hinder  end. 
These  red  tubercles  are  very  distinctive  and  give  a  positive  recognition  of  this 
caterpillar. 

The  hairs  just  mentioned  are  delicate,  brittle,  barbed  in  some  cases,  and 
secrete  a  poisonous  fluid  very  irritating  to  the  skin.  As  the  caterpillars  molt 
these  hairs  are  liable  to  be  broken  off  and  carried  through  the  air  to  persons  or 
onto  their  clothing,  and  a  painful  rash  somewhat  resembling  that  caused  by 
poison  ivy  is  produced,  known  as  the  "  brown-tail  rash." 

Pupation  usually  occurs  among  the  leaves  and  after  about  20  days  is  followed 
by  the  emergence  of  the  adult  moths.  The  cocoon,  though  more  developed  than 
with  the  Gypsy  Moth,  is  not  very  thick  or  dense,  and  the  pupa  can  generally  be 
seen  through  its  walls. 

Control — Cutting  off  and  burning  the  winter  tents  at  any  time  between  Sep- 
tember and  April  is  an  effective  method  of  control  where  the  size  of  the  tree  is 
such  that  the  tents  can  easily  be  reached.  Spraying  with  arsenate  of  lead, 
standard  formula,  either  in  the  fall  if  no  fruit  is  involved,  or  when  the  larvae 
first  resume  feeding  in  the  spring,  is  also  a  good  treatment. 

Many  of  the  parasites  imported  by  the  Federal  Government  to  destroy 
the  .Gypsy  Moth,  attack  this  species  also  and  appear  to  have  done  good  work. 
For  the 'last  few  years  this  insect  has  been  rather  less  abundant  than  was  pre- 
viously the  case.  Whether  this  condition  will  continue,  or  outbreaks  will  recur 
from  time  to  time  cannot  now  be  determined,  but  probably  the  latter  will  be 
true. 

Family  Notodontidse  (The  Prominents). — The  Prominents  as  the  insects 
of  this  family  are  often  called,  are  of  medium  size  as  adults  and  usually  not  at  all 
brilliantly  colored.  Few  of  them  are  serious  pests,  and  then  generally  only  for 
a  year  or  two  at  a  time.  The  caterpillars  of  the  different  species  differ  greatly 
in  appearance,  some  having  dorsal  humps  or  projections,  others  a  much  elongated 
end  of  the  body,  or  other  modification  of  the  typical  form  of  caterpillar. 


THE  LEPIDOPTERA 


267 


One  part  of  this  family  consists  of  moths  known  as  the  Datanas.  The  larvas 
of  these  insects  feed  on  orchard,  shade  and  forest  trees,  keeping  together  in 
groups,  and  when  resting  or  disturbed  they  bend  the  ends  of  the  body  nearly. at 
right  angles  to  the  middle  part,  in  a  very  characteristic  attitude.  They  feed 
during  July  and  August  and  when  full-grown  are  about  two  inches  long.  One 
species  is  common  on  the  apple  (Figs.  270,  271) :  others  occur  on  the  oak,  walnut, 
hickory  and  other  plants.  The  presence  of  100  or  200  caterpillars  feeding  to- 
gether on  a  single  branch,  and  of 
considerable  size  as  they  get  older, 
often  disturbs  the  owners  of  infested 
trees  who  unnecessarily  fear  serious 
injury  to  "their  trees. 

The  fact  that  the  caterpillars  feed 
in  groups  renders  control  easy,  how- 
ever, either  by  removing  the  groups  by 
hand  or  by  spraying  the  region  at- 
tacked, with  a  stomach  poison,  which 
is  very  effective  for  these  insects. 

Another  Notodontid  having  similar 
habits  and  found  at  the  same  season 
is  the  Red-humped  Apple-tree  Cater- 
pillar (Schizura  concinna  S.  &  A., 
Fig.  272).  The  larva  (Fig.  273)  has  a 
red  head ;  a  red  hump  a  short  distance 
behind;  a  double  row  of  black  spines 


FIG.  270.  FIG.  271. 

FIG.  270. —  Adult  Moth  of  Yellow-necked  Apple-tree  Caterpillar  (Datana  ministra 
Dru.),  slightly  less  than  natural  size.  (Original.) 

FIG.  271. — Yellow-necked  Apple-tiee  Caterpillars  on  a  branch,  showing  characteristic 
attitudes  assumed  when  disturbed.  Natural  size.  (From  Britton,  Eighteenth  Kept.  Ent. 
Conn.  Agr.  Exp.  Sta.  1918.) 

along  its  back;  and  its  body  is  narrowly  striped  with  yellow,  black  and  white. 
Control  is  the  same  as  for  the  Datanas. 

Family  Dioptidae. — This  family  appears  to  have  but  one  North  American 
representative,  found  only  on  the  Pacific  Slope.  It  is  known  as  the  California 
Oak  Worm  (Phryganidia  calif ornica  Pack.),  and  the  caterpillar  feeds  upon  the 
leaves  of  the  live  oak  and  deciduous  oaks.  The  adult  moth  (Fig.  274)  is  light 
brown  with  darker  veins  and  a  wing-spread  of  about  an  inch  and  a  quarter. 
The  eggs  are  laid  on  the  leaves  of  the  oaks  and  various  other  plants  in  October 


268 


APPLIED  ENTOMOLOGY 


and  November,  and  hatch  during  the  5  months  following.  Those  on  the  decidu- 
ous oaks  fall  with  the  leaves,  and  larvae  from  them  rarely  find  anything  to  feed 
upon  and  therefore  die.  The  eggs  laid  on  the  live  oak,  eucalyptus  and  chestnut, 
however,  produce  caterpillars  (Fig.  275)  which  can  generally  obtain  food  and 
they  become  full-grown  in  May  and 
June  and  pupate  in  any  protected 
place,  spinning  no  cocoon.  The 
moths  from  these  pupa3  emerge  after 
about  2  or  3  weeks  and  lay  their  eggs 
for  a  second  generation,  the  larvae  of 
which  feed  during  the  last  of  July, 
August  and  September.  Pupation  fol- 
lows, after  which  the  moths  appear 
and  lay  their  eggs  as  already  indicated. 


FIG.  272. 


FIG.  273. 


FIG.  272.  —  Adult  Moth  of  Red-humped  Apple-tree  Caterpillar  (Schizura  concinna  S. 
and  A.),  natural  size.  (Original.) 

FIG.  273.  —  Red-  humped  Apple-tree  Caterpillar  in  feeding  position.  Somewhat  en- 
larged. (From  Britton,  First  Ript.  Ext.  Conn.  Agr.  Exp.  Sta.  1901.) 

When  abundant,   the  trees  upon  which  these  insects  feed  are  liable  to  be 
entirely  stripped  of  their  foliage  and  this  sometimes  happens  over  large  areas. 

Control.  —  Spraying  the  trees  when  the  caterpillars  are  abundant,  as  they 
begin  to  feed,  with  Arsenate  of  lead,  4  or  5  Ib.  of  the  paste  (2  or  2%  Ib.  of  the 


FIG.  274.  FIG.  275. 

FIG.  274. — California  Oak  Worm  Moth  (Phryganidia  calif ornica  Pack.),  about  natural 
size.  (After  Essig,  Inj.  and  Benef.  Ins.  of  Cal.) 

FIG.  275. — Caterpillar  of  the  California  Oak  Worm,  natural  size.  (Modified  from 
Essig,  Inj.  and  Bencf.  Ins.  of  Cal.) 

powder)  in  50  gal.  of  water  is  effective  where  the  size  of  the  trees  permits  this 
treatment.  Power  sprayers  and  nozzles  giving  a  fine  mist  are  the  most  effective 
for  this  purpose. 

Family  Noctuidae  (The  Owlet  Moths). — The  Noctuids  form  the  largest 
family  of  moths  in  this  country  and  are  everywhere  abundant.  Within 


THE  LEPIDOPTERA 


269 


the  group  there  are  great  differences  in  the  appearance  of  the  moths 
and  in  the  habits  of  their  larvae.  Lochhead  has  divided  the  family  into 
nine  sections,  based  mainly  on  differences  of  larval  habits. 

Some  members  of  the  Noctuidse  are  known  as  the  Catocalas  or  "Under- 
wings."  Some  of  these  are  quite  large,  spreading  three  inches  or  more,  the  fore 
wings  with  quiet  colors  and  marked  so  that  they  resemble  the  bark  of  trees  (Fig. 
276) .  One  has  fore  wings  similar  to  the  bark  of  the  white  birch :  another  resembles 
the  bark  of  the  beech,  and  many  kinds  of  trees  are  thus  imitated  in  color  and 
markings.  The  hind  wings  are  brightly,  often  brilliantly  colored  and  it  appears 
to  be  the  habit  of  the  moths,  which  fly  at  night,  to  rest  during  the  day  on  the  tree 
trunks  whose  bark  their  fore  wings  resemble,  folding  these  over  their  gaudy  hind 
wings,  in  this  way  obtaining  through  concealment,  protection  from  their  enemies. 
How  far  in  the  course  of  thousands  of  generations,  the  weeding  out  by  these 
enemies  of  those  least  closely  resembling  the  bark,  leaving  behind  to  continue 


FIG.  276. — Catocala  Moth,  natural  size.     (Original.) 

the  race  the  closest  imitators  of  the  bark,  has  resulted  in  giving  to  the  present 
members  of  the  group  a  closer  resemblance  than  their  ancestors,  is  a  question  for 
speculation.  The  larvae  of  the  Catocalas  feed  on  foliage  but  are  rarely  if  ever 
injurious  enough  to  be  of  importance. 

The  largest  Noctuid  found  in  this  country  is  known  as  the  Black  Witch 
(Erebus  odorata  L.).  It  does  not  live  in  the  United  States,  being  an  inhabitant 
of  the  tropics,  but  its  size  and  powerful  wings  which  often  spread  six  inches, 
enable  it  to  fly  long  distances  and  it  is  often  captured  in  the  late  summer  and 
fall  in  the  Northern  United  States.  It  has  dark  wings  of  various  shades  of 
brown,  and  a  small  "eye"  spot  in  each  fore  wing. 

The  Cotton  Worm  (Alabama  argillacea  Hbn.). — The  Cotton  Worm  is  not  a 
native  of  this  country  but  of  more  tropical  countries,  from  which  it  frequently 
comes  and  attacks  cotton  in  the  Southern  States.  The  moths  (Fig.  277)  are  of  a 
nearly  uniform  reddish-brown  or  tawny  color,  and  spread  a  little  over  an  inch. 
They  lay  their  eggs  singly  on  the  cotton  leaves  and  these  eggs  hatch  in  from  3 
to  more  than  20  days,  according  to  the  temperature.  The  caterpillars  are  at 
first  yellowish-green  with  pale  yellow  heads.  Later  they  vary  much  in  color  and 
markings,  some  changing  little,  while  others  acquire  a  black  stripe  along  the 
middle  of  the  back,  with  a  fine  central  yellow  line,  and  each  segment  has  four 


270  APPLIED  ENTOMOLOGY 

black  dots  above.  The  full-grown  larva  webs  a  leaf  or  two  together  and  pupates 
in  this  place,  remaining  there  a  varying  length  of  time  before  the  adult  emerges. 
Fall  nights  northward  of  Cotton  worm  moths  occur  frequently  and  may 
extend  into  the  Northern  States  and  Canada,  where  these  insects  are  sometimes 
found  abundantly  in  September  and  October. 

Control. — Dry  arsenate  of  lead  dusted  over  the  plants  when  these  insects 
first  appear,  using  from  2  to  4  Ib.  per  acre,  according  to  the  size  of  the  plants, 

appears  to  be  a  satisfactory  treatment. 
It  is  usually  applied  while  the  dew  is  on 
the  plants. 

The  Dagger  Moths  are  leaf  feeders  on 
various  shrubs  and  trees  in  their  larval 
stages.  The  fore  wings  of  the  moths  are 
various  shades  of  gray  in  most  cases,  and 
the  larvae  are  usually  quite  well  covered  by 
rather  uniformly  distributed  gray  hairs. 
Several  species  are  known  as  Green  Fruit 


n  w  m°th   °V7 the      worms,  the  caterpillars  being  greenish,  with- 

Cotton   Worm    (Alabama    argillacea  '  ** 

Hbn.),  about  natural  size.  (Original.)      out    hairs,    and  feeding  on  the  leaves  and 

small  fruit  of  apple  and  other  trees  during 
the  later  spring  months.     They  are  not  often  seriously  abundant. 

Some  of  the  Noctuids  are  Stalk  Borers,  tunneling  in  the  stems  of  cultivated 
and  other  plants,  among  the  plants  affected  in  this  way  being  corn,  tomatoes, 
potatoes,  asters,  dahlias,  etc.  The  larva  feeds  during  the  summer  months  and 
as  a  rule  pupates  in  the  lower  part  of  its  tunnel.  Accordingly,  all  wilted  plants 
should  be  examined,  and  if  a  borer  is  present  the  plant  should  be  destroyed 
with  the  borer  either  as  larva  or  pupa,  within  it. 

The  Corn  Ear  Worm  (Chloridea  obsoleta  Fab.). — This  widely  distrib- 
uted pest  is  known  by  several  common  names,  such  as  the  Cotton  boll- 
worm,  tomato  fruitworm  and  false  budworm  of  tobacco,  iri  addition  to 
the  one  first  given.  In  the  South  it  attacks  cotton  bolls  and  tobacco  seed 
pods,  as  well  as  tomatoes  and  corn  which  are  its  usual  food  in  the  North. 
It  is  present  practically  everywhere  in  the  world  between  the  parallels  of 
50°  north  and  south  latitude,  and  its  original  home  is  problematical. 

The  adult  insect  (Fig.  278a)  spreads  about  an  inch  and  three-quarters 
and  is  extremely  variable  in  color,  so  that  several  varieties  have  been 
recognized.  It  ranges  from  a  pale  reddish-brown  to  olive,  with  a  greenish 
tinge  toward  the  outer  margin  of  the  .fore  wings,  with  darker  bands  and 
spots,  and  the  hind  wings  are  lighter,  with  dark  veins  and  a  blackish 
shade  crossing  from  one  outer  angle  to  the  other,  leaving  more  or  less  of  a 
lighter  color  between  this  and  the  outer  margin. 

The  insect  appears  to  pass  the  winter  as  a  pupa  in  the  ground,  the 
adult  emerging  in  the  spring,  earlier  in  the  South  and  later  farther  North. 
The  eggs,  varying  in  number  from  less  than  500  to  nearly  3,000  are  now 
laid  on  different  parts  of  the  food  plants  and  on  weeds  or  even  on  the 
ground.  They  hatch  in  a  week  or  less,  according  to  the  temperature,  and 


THE  LEPIDOPTERA 


271 


the  larvae  (Fig.  2786)  begin  feeding,  at  first  on  the  surface  of  the  plant 
but  soon  boring  into  it  at  some  tender  place. 

With  cotton,  injury  is  caused  by  eating  out  the  squares  and  the  more 
tender  bolls.  In  the  case  of  corn  the  first  attack  is  by  boring  into  the 
bud  and  eating  down  into  the  developing  leaves.  Later,  the  tassels  are 
often  injured  before  they  open,  and  after  the  silk  appears  eggs  are  laid  on 
this  and  the  caterpillars  which  hatch  from  them  bore  into  the  ears  of  corn  to 
varying  distances,  often  entirely  destroying  the  ears,  particularly  in  the 
case  of  sweet  corn.  Tomatoes  are  injured  mainly  by  the  larvae  boring 


FIG.  278. — Corn  Ear  Worm  (Chloridea  obsolela  Fab.) :  a,  adult  moth;  b,  larva;  d,  pupa:  all 
enlarged.     (From  U.  S.  D.  A.  Farm.  Butt.  890.) 


into  the  green  or  partially  ripened  fruit,  and  in  some  cases  by  boring  into 
the  tips  of  the  plants  or  eating  the  blossoms.  With  tobacco  the  larvae 
attack  the  bud  leaves  at  the  tip  of  the  plant  and  later  bore  into  the  pods. 
Peaches,  peas,  beans,  etc.,  are  also  sometimes  injured  and  the  average 
annual  loss  by  the  ravages  of  this  pest  in  the  United  States  has  been  esti- 
mated as  over  eighteen  million  dollars. 

There  are  several  generations  of  this  insect  each  year,  four  or  five 
being  produced  in  the  far  South  and  this  number  reducing  northward 
until  in  the  Northern  States  and  Canada  there  is  but  one.  The  larvae 
vary  greatly  in  color  and  markings  and  are  most  easily  recognized  by  the 
nature  of  their  work.  When  full-grown  they  are  about  an  inch  and  a 
half  long. 


272  APPLIED  ENTOMOLOGY 

Control. — Late  fall  plowing  to  break  up  the  earthen  cells  in  the  ground 
where  the  insects  winter  as  pupae,  provided  the  plowing  is  rather  deep, 
is  a  helpful  procedure.  As  the  larvae  feed  for  a  short  time  on  the  surface 
of  the  plants  before  boring  into  them,  the  application  of  arsenate  of  lead 
at  or  just  before  this  time,  is  advantageous.  With  the  increasing  num- 
bers in  the  later  generations  of  the  insect,  fertilization,  culture  and  any 
methods  possible  for  hastening  the  maturity  of  the  crop  are  desirable. 
Green  corn  is  the  preferred  food  plant  of  this  insect  and  rows  of  corn 
planted  in  and  near  cotton  fields,  if  in  tassel  and  silk  about  the  first  of 
August  will  attract  most  of  the  moths,  leaving  the  cotton  much  more  free 
than  otherwise.  On  corn  itself,  dusting  powdered  arsenate  of  lead  onto 
the  silks,  as  soon  as  these  appear,  seems  to  reduce  the  damage  to  quite  an 
extent  if  applied  at  3  or  4-day  intervals  while  the  silk  is  developing. 

In  the  Noctuidae  are  a  number  of  species  where  some  of  the  abdominal 
feet  of  the  caterpillars  are  not  functional  or  are  absent,  as  a  result  of 
which  these  larvae  travel  like  those  of  the  Geometers  or  "inch  worms" 
already  described.  Several  of  these  species  are  occasionally  injurious  to 
cultivated  plants.  In  most  cases  at  least,  such  larvae  can  be  controlled 
by  the  application  of  arsenate  of  lead. 

The  Army  Worms  also  are  members  of  the  Noctuidae,  this  name  being 
given  to  the  insects  because  of  their  habit  of  marching  from  place  to  place 
all  together,  like  armies.  They  are  periodically  injurious  insects,  appear- 
ing in  great  abundance  at  times,  but 
rarely  troublesome  for  more  than  one 
season  at  a  time  in  the  same  place. 

The  Army  Worm  (Cirphis  uni- 
puncta  Haw.). — This  pest  is  probably 
a  native  of  North  America.  It  occurs 
over  the  entire  eastern  United  States 
as  far  west  as  Kansas  and  Nebraska, 


FIG.  279. — Adult  Moth  of  the  Army    and    has    been    reported    from    the 

Southwestern  States  and  California. 
The  adult  moth  (Fig.  279)  spreads 
about  an  inch  and  a  half,  and  is  quite  uniformly  brownish-gray  with  a 
tiny  white  spot  near  the  middle  of  each  front  wing  and  a  rather  dusky 
outer  margin  on  the  hind  wings.  The  moths  fly  at  night  and  are  often 
attracted  to  lights. 

In  what  stage  this  insect  passes  the  winter  does  not  appear  to  have 
been  conclusively  proved,  but  it  is  probably  as  the  partly  grown  cater- 
pillar hiding  in  rank,  dense  weedy  growth.  In  late  spring,  at  least, 
the  nearly  full-grown  larvae  have  been  found  /ceding  on  grasses  primarily 
and  then  on  small  grain.  The  larvae  mature  quite  rapidly,  pupate  in  the 
ground  and  produce  the  moths  in  June,  at  least  in  the  North.  Eggs 
are  now  laid  on  grass  and  similar  plants  and  hatch  in  8  or  10  days 


THE  LEPIDOPTERA 


273 


and  the  larva  feeds  for  3  or  4  weeks  until  about  an  inch  and  a  half  long. 
It  is  now  a  nearly  naked  caterpillar  (Fig.  280),  somewhat  variable  in 
color  but  generally  rather 
greenish,  with  a  broad  dark 
stripe  along  its  back  with  a 
fine,  broken,  white  line  along 
its  middle,  and  a  dark  stripe 
along  each  side. 

Before  this  size  has  been 
attained  all  the  food  where 
these  insects  are,  may  have 
been  consumed  if  the  larvse 
are  abundant,  and  in  this  case 
they  march  off  in  armies  to 
find  new  feeding  grounds, 
and  it  is  these  marching 
armies  which  usually  attract 
attention  in  July  or  August. 
When  feeding  has  been  com- 
pleted they  pupate  in  the 
ground  and  the  moths  emerge 
in  September  or  October  and 
probably  lay  eggs  which  soon 
hatch,  the  caterpillars  thus 
produced,  feeding  to  some  ex- 
tent before  winter.  The 
spring-feeding  generation  ap- 
pears to  be  little  noticed,  the 
destruction  seen  being  by  the 
summer  generation. 

When  the  caterpillars  are 
abundant  numerous  flies  re- 
sembling, but  larger  than 
house-flies,  and  called  "ta- 
china  flies,"  are  usually 
noticed  flying  about  the 
army.  These  are,  nearly  al- 
ways at  least,  parasites  laying 
their  eggs  on  the  caterpillars. 

The     maggots     which     hatch         FIG.  280.— Army  Worm  Caterpillars  feeding  on 

from  these  eggs  bore  into  the    c°rn;  1BINa*ural  s;ze-     <FrT  Britt™>  fourteenth 

...  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1914.) 

caterpillars  and  feed  upon  and 

finally  kill  them.    There  are  also  several  other  insect  enemies  of  the 

Army  Worm. 

18 


274  APPLIED  ENTOMOLOGY 

Control. — If  Army  Worms  are  discovered  before  they  begin  their 
march,  spraying  all  the  plants  where  they  are  with  a  stomach  poison 
is  an  effective  treatment,  or  if  the  infested  area  is  small,  straw  can  be 
spread  over  it  and  burned.  Once  on  the  march,  protection  of  any  crops 
towards  which  the  caterpillars  are  marching,  either  by  destroying  the 
insects  or  by  preventing  their  reaching  the  crops,  is  the  aim  of  any  treat- 
ment. Poisoned  baits  (see  under  "  Cutworms,"  page  276)  may  be  used  for 
this  purpose,  or  where  the  ground  over  which  the  insects  are  marching 
is  fairly  smooth  and  firm,  the  use  of  a  heavy  roller  is  possible.  A  ditch 
dug  across  their  line  of  march  or  around  an  infested  area  is  often  used, 
and  a  log  dragged  along  in  the  ditch  as  the  caterpillars  become  thick  in  it 
will  kill  multitudes.  Food  in  a  strip  ahead  of  their  line  of  march,  sprayed 
with  a  stomach  poison  will  result  in  the  poisoning  of  those  which  feed 
there,  and  in  some  cases  the  caterpillars  while  marching  can  be  reached 
and  killed  by  a  strong  contact  insecticide. 

The  Fall  Army  Worm  (Laphygma  frugiperda  S.  &  A.). — This  insect  in 
many  ways  resembles  the  true  Army  Worm.  It  has  numerous  common 
names  such  as  the  "grassworm,"  " overflow  worm,"  " alfalfa  worm," 
etc.,  and  it  is  called  the  Fall  Army  Worm  only  in  the  Middle  and  Northern 
States,  as  it  does  not  appear  there  before  fall. 


FIG.  281.  FIG.  282. 

FIG.  281. — Moth  of  Fall  Army  Worm  (Laphygma  frugiperda  S.  and  A.),  about  natural 
size.  (Modified  from  U.  S.  D.  A.  Farm.  Bull.  7f-2.) 

FIG.  282. — Full-grown  Caterpillar  of  Fall  Army  Worm,  somewhat  enlarged.  (Modified 
from  U.  S.  D.  A.  Farm.  Bull.  752.) 

This  insect  is  probably  a  native  of  this  country.  While  most  destruc- 
tive in  the  South  it  may  spread  during  the  season  far  to  the  North, 
reaching  the  New  England  States,  southern  Wisconsin  and  south- 
eastern Montana,  and  extending  westward  to  the  Rocky  Mountains. 

The  moth  (Fig.  281)  spreads  about  an  inch  and  a  quarter.  Its  front 
wings  are  mottled  gray,  usually  with  a  light  spot  near  the  tip,  and  the 
hind  wings  pearly  white,  edged  with  a  rather  narrow,  dark  line.  It  does 
not  seem  to  be  able  to  live  over  winter  north  of  the  southern  parts  of  the 
Gulf  States.  The  caterpillar  (Fig.  282)  feeds  upon  native  grasses  pri- 
marily, but  when  these  are  not  sufficiently  abundant  it  may  attack 
grains,  sorghum,  alfalfa,  clover,  cotton  and  other  crops. 

In  what  stage  this  insect  spends  the  winter  does  not  seem  to  have 
been  positively  determined,  but  it  is  probably  the  pupa.  The  eggs, 


THE  LEPIDOPTERA 


275 


from  50  to  several  hundred  in  number,  are  laid  preferably  on  grass  blades 

and  in  the  South  hatch  in  a  few  days.     The  caterpillars  feed  2- or  3  weeks 

before  reaching  full  size  and  are  then  very  similar  to  those  of  the  Army 

Worm.     They  then  pupate  for  10  to  14 

days  in  the  ground,  after  which  the  adult 

moths  emerge.     Many  of  these  moths 

now  fly  northward,  often  several  hundred 

miles,  before  laying  their  eggs,  and  in 

this  new  location  another  generation  is 

produced,  the  adults  of  this  generation 

also  flying  northward  to  lay  their  eggs. 

In   this   way   the  northern  part  of  the 

country  becomes  infested  in  the  fall  but 

frost  puts  an  end  to  the  development  of 

these  insects  near  their  northern  limits 

before  more  than  one  generation  can  be 

produced.     Going  southward,  more  are 

possible,  and  in  the  Gulf   States  there 

may  be  six  in  the  course  of  a  season. 


FIG.  283. — Dingy  Cutworm  (Feltia 
subgothica  Haw.) :  a,  moth,  wings 
spread;  b,  larva  (Cutworm) ;  c,  Moth, 


Where  corn  and  cotton  are  grown  the    Wln^s  f  olded-    AU  somewhat  enlarged. 

.,      WT    .          \  .       f  (From  U.  S.  D.  A.  Farm.  Bull.  856.) 

destruction  caused  by  this  insect  is  often 

very  great,  the  caterpillars  as  they  get  large  having  voracious  appetites. 

They  usually  feed-  more  at  night  than  during  the  daytime,  and  like  the 

Army  Worm,  march  to 
other  places  to  find  food 
when  the  supply  where  they 
are  becomes  exhausted. 

In  general  the  methods 
used  for  controlling  the 
Army  Worm  apply  to  this 
insect  also. 

A  number  of  other 
species  of  Noctuids  have 
the  habit  of  marching  in 
armies  when  their  food  be- 
comes scarce.  Their  life 
histories  and  habits  are  for 
the  most  part  quite  similar 

f     ±  ^  r  f^      f          qr»prip<5 

tWO  sPecles 

already  described,  and  COn- 
trol  methods  for  them  are 

generally  the  same. 

Still  another  section  of  this  family  occurs,  widely  distributed,  and 
causing  much  injury.  The  insects  of  this  division  are  called  Cutworms 
(Figs.  283  and  284)  because  of  the  habit  of  the  larvse  of  feeding  on  the 


FIG.  284.—  Cotton-boll  Cutworm  (Prodenia  ornitho- 
galli  Guen.):  a,  light  form  of  Cutworm;  6,  dark  form; 
dark  form  of  Moth  above;  pale  form  below.  All  some- 
what  enlarged.  (From  U.  S.  D.  A.  Farm.  Bull.  890.) 


276  APPLIED  ENTOMOLOGY 

stems  of  succulent  plants  at  about  the  level  of  the  ground  and  thereby 
either  partially  or  entirely  cutting  them  off  at  this  point.  Several 
hundred  species  have  this  habit  and  many  kinds  of  garden  and  field 
crops  suffer  in  this  manner  during  the  spring  and  early  summer  months. 
A  few  have  the  habit  of  climbing  up  the  plants  at  night  and  feeding 
there,  some  distance  above  the  ground. 

The  moths  are  usually  of  medium  size,  spreading  from  an  inch  to 
about  two  inches,  and  are  generally  quiet  colored,  gray,  brown  or  blackish, 
more  or  less  mottled,  streaked  or  banded  on  the  fore  wings  while  the 
hinder  pair  are  nearly  white  and  unmarked  except  for  darker  margins  in 
some  cases.  Some  species  are  more  strongly  marked,  however,  and  have 
brighter  colors. 

Most  of  these  insects  winter  either  as  pupae  or  partly  grown  cater- 
pillars. In  the  spring  the  latter  pass  the  day  in  the  ground,  coming  up 
at  night  to  feed.  They  are  generally  dull  colored  with  rather  faint  spots 
and  lines  and  without  a  hairy  covering,  and  when  full-grown  will  average 
an  inch  to  an  inch  and  a  half  in  length.  When  feeding  has  been  completed 
they  pupate  a  few  inches  deep  in  the  ground.  Some  species  have  one 
generation  each  year;  others  two. 

Control. — Late  fall  plowing  to  bring  up  and  expose  the  insects  to  the 
fluctuating  temperatures  of  the  cold  season  and  its  rains,  is  a  useful 
treatment,  but  other  measures  are  also  necessary.  When  Cutworm 
work  is  seen  the  use  of  a  pois'on  bait  is  desirable.  Fo-r  this  purpose  one 
good  formula  is: 

LARGE  FOR  SMALL 

QUANTITY  GARDENS 

Bran 50  Ib.  or    1      pk. 

Paris  green 2  Ib.  or  Y^       Ib. 

Cheap  molasses 2  qt.  or    1      pt. 

Oranges  or  lemons 3  fruits  or    1      fruit 

Water 3  to  7  gal.  or    4  to  6  qt. 

The  second  formula  is  for  use  where  only  a  small  quantity  is  desired. 

Mix  the  bran  and  Paris  green  together  thoroughly,  dry:  add  the 
juice  of  the  fruit  to  some  of  the  water- and  chop  up  the  rest  of  the  fruit 
finely  and  add  this  and  the  molasses.  Now  combine  this  mixture  with 
the  bran  and  Paris  green  and  stir  thoroughly,  adding  enough  more 
water  to  finally  produce  a  rather  stiff  dough.  This  can  be  used  in 
gardens,  placing  about  a  teaspoonful  close  to  the  base  of  each  plant  liable 
to  attack,  but  should  be  put  on  toward  night  so  that  it  will  not  dry  up 
in  the  sun  and  lose  its  attractiveness  to  the  Cutworms.  Fowls  should 
be  shut  up  while  this  treatment  is  being  used,  to  prevent  their  feeding 
on  the  bait  and  being  poisoned. 

Where  large  fields  are  to  be  treated,  a  modification  of  this  formula 
is  desirable,  reducing  the  amount  of  water  to  a  point  where  the  mixture 
is  dry  enough  to  spread  broadcast,  yet  wet  enough  so  that  each  flake  of 


THE  LEPIDOPTERA 


277 


bran  has  been  moistened  by  the  molasses  and  fruit  juice  sufficiently  to 
make  it  attractive,  and  also  bears  a  little  of  the  poison.  The  amount  of 
water  to  add  to  obtain  this  condition  must  be  determined  by  testing  the 
mixture  at  intervals  to  see  that  the  bran  is  dry  enough  to  spread,  and 
also  that  it  has  been  able  to  take  up  the  other  materials.  In  any  case  the 
mixture  should  stand  for  several  hours  before  use,  to  allow  the  bran  time 
to  take  up  the  other  constituents.  The  larger  quantity  given  above  is 
sufficient  to  spread  broadcast  over  several  acres. 

The  size  of  the  family  Noctuidse  and  the  abundance  of  its  members 
in  all  parts  of  the  country,  as  well  as  the  various  methods  of  feeding 
present  in  the  group  make  it  one  of  the  most  destructively  important 
families  of  Lepidoptera  in  the  United  States. 

Family  Arctiidae  (The  Tiger  Moths). — The  Arctiids  are  mainly  medium-sized 
moths,  often  brilliantly  colored.  Most  of  the  group  are  not  serious  pests,  but 
individuals,  particularly  in  their  larval  stage,  are  often  seen.  Many  of  these 
caterpillars  are  quite  densely  and  uniformly  covered  with  long  hairs  and  are 
sometimes  called  "  woolly  bears."  One  of  them  often  seen  crawling  about  in  the 


FIG.  285.  FIG.  286. 

FIG.  285.— Isabella  Tiger  Moth  (Isia  Isabella  S.  and  A.),  slightly  reduced.     (Original.) 
FIG.  286. — Hickory    Tiger    Moth     (Halisidota    caryce    Harr.),    natural    size.       (From 
Britton,  Seventh  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1907.) 


fall  is  covered  with  reddish-brown  hairs  at  each  end,  and  black  ones  in  the  middle, 
and  is  sometimes  given  the  particular  name  "  hedgehog  caterpillar."  The  adult 
(Fig.  285),  not  often  seen,  is  an  orange-buff  moth,  its  hind  wings  tinged  with 
pinkish,  and  spreads  a  little  over  two  inches.  It  is  called  the  Isabella  Tiger  Moth 
(Isia  isabella  S.  &  A.).  Another  caterpillar,  the  " salt-marsh  caterpillar"  (Estig- 
mene  acrcea  Dru.)  has  a  blackish  head  and  body,  well  covered  with  long,  tufted, 
brownish  hairs.  The  adult  is  about  the  size  of  the  Isabella  Tiger  Moth,  the  male 
having  white  fore  wings  spotted  here  and  there  with  black,  while  the  female  has 
all  its  wings  white  and  spotted.  The  abdomen  of  both  sexes  is  orange.  The 
Hickory  Tiger  Moth  (Halisidota  caryce  Harr.,  Fig.  286)  is  quite  common  in  the 
northeastern  United  States  and  Canada,  west  to  Minnesota  and  south  to  North 
Carolina  and  Ohio.  The  larvae,  which  occur  in  the  summer  and  fall,  feed  on 
many  kinds  of  trees  and  are  sometimes  rather  injurious.  At  first  tjiey  feed  in 
company  but  during  the  latter  part  of  their  larval  life  they  scatter.  The  full- 


278 


APPLIED  ENTOMOLOGY 


grown  larva  (Fig.  287)  is  an  inch  and  a  quarter  or  more  in  length,  covered  with 
grayish-white  and  black  hairs.  Along  the  middle  of  the  back  is  a  row  of  tufts 
of  black  hairs  and  there  may  also  be  longer,  slender  black  tufts  or  "  pencils." 
The  insect  winters  as  the  pupa  under  rubbish  on  the  ground,  and  the  moths 
emerge  in  late  spring  and  early  summer  and  are  yellowish  in  color,  the  fore  wings 
sprinkled  with  brown  dots  and  two  brownish  streaks.  These  wings  are  rather 
narrow  for  their  length,  and  somewhat  pointed.  The  hind  wings  are  nearly 

transparent  and  almost  white.  The  moths 
spread  about  two  inches.  Control  is  by 
spraying  with  a  stomach  poison  as  soon 
as  the  work  of  the  caterpillars  is  noticed. 

The  Fall  Webworm  (Hyphantria 
cunea  Dru.). — This  insect  is  a  pest  on 
shade,  fruit,  and  ornamental  trees. 
It  is  found  everywhere  in  the  eastern 
United  States  and  as  far  west  as 
Montana  and  Texas.  In  the  South 
and  northward  about  to  New  York 
there  are  two  generations  each  year 
and  a  correspondingly  greater  amount 
of  injury  than  where  one  is  the  rule. 


FIG.  287.  FIG.  288. 

FIG.  287. — Full-grown  Caterpillar  of  the  Hickory  Tiger  Moth,   natural  size.     (From 
Britton,  Seventh  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1907.) 

FIG.  288. — Fall  Webworm  (Hyphantria  cunea  Dru.),   about  natural  size.     (Original.) 

The  adult  moth  (Fig.  288)  spreads  about  an  inch,  and  in  the  north 
has  pure  white  wings.  Farther  south  black  spots  are  present  on  them 
and  this  difference  has  led  to  the  belief,  still  held  by  some  persons,  that 
there  are  really  two  species  concerned.  The  winter  is  spent  as  the  pupa 
in  the  ground,  the  moths  emerging  in  the  late  spring  and  laying  their 
eggs  in  clusters,  often  200  or  300  in  number,  on  the  under  side  of  the 
leaves.  These  hatch  in  about  10  days  and  the  larvae  pass  together 
to  the  outer  foliage  of  some  branch,  where  they  form  a  thin  white  web 
over  the  surface,  feeding  on  the  leaves  enclosed  within  the  web  (Fig. 
289).  As  the  caterpillars  grow  and  consume  this  foliage,  the  web  is 
extended  to  cover  more  leaves  and  by  the  time  full  size  has  been  attained 
by  the  caterpillars,  the  web  may  be  as  large  as  a  bushel  basket.  The 
full-grown  larva  (Fig.  290)  is  over  an  inch  long,  quite  hairy  but  not 


THE  LEPIDOPTERA 


279 


sufficiently  so  to  conceal  the  body  which  is  generally  "  pale-yellowish  or 
greenish,  with  a  broad,  dusky  stripe  along  the  back  and  a  yellow  stripe 
along  the  sides;  they  are  covered  with  whitish  hairs  which  spring  from 


FIG.  289. — Branch  covered  by  web  of  the  Fall  Webworm. 

Bull.  139.) 


(From  N.  H.  Agr.  Exp.  Sta. 


black  and  orange-yellow  warts"  (Packard).     The  head  is  black.     The 
larvae  pupate  in  the  ground. 

Where  there  are  two  generations  the  moths  appear  in  June  or  even 
earlier  and  the  second  generation  moths  develop  early  enough  in  the 

fall  for  the  larvae  from  their  eggs  to  become  full-    _ 

grown  before  the  leaves  drop.  Where  there  is 
but  one  generation  the  webs  appear  the  last  of 
July  and  in  August,  and  reach  full  size  in 
September. 

Control. — There  are  several  ways  'by  which 
to  check  the  ravages  of  this  insect.  When  the 
webs  first  appear  they  may  be  stripped  off  by  hand  and  the  then 
small  larvae  crushed.  Branches  attacked  may  be  cut  off  if  the  tree  is 
of  sufficient  size  not  to  be  marred  in  this  way.  Spraying  all  around 
the  tent  with  a  stomach  poison,  standard  formula,  will  poison  the  leaves 
next  to  be  brought  within  the  web  by  its  further  enlargement,  and  thus 
provide  the  caterpillars  with  poisoned  food. 


FIG.  2 9 0 .—Full-grown 
larva  of  the  Fall  Webworm, 
natural  size.  (Original.) 


280 


APPLIED  ENTOMOLOGY 


Family  Ceratocampidse  (The  Royal  Moths).— In  this  family  are  included 
several  very  large  moths  and  a  few  smaller  ones.  The  Regal  Walnut  Moth 
(Citheronia  regalis  Fab.)  may  have  a  wing-spread  of  six  or  seven  inches  (Fig.  291). 
Its  fore  wings  are  rather  dusky  but  the  veins  are  lined  with  orange-red  and  there 
are  numerous  yellow  spots.  The  hind  wings  are  lighter,  with  some  yellowish  areas, 
and  veins  lined  as  in  the  other  pair.  The  stout  body  is  brownish-orange  with 


FIG.  291. — Regal  Walnut  Moth  (Cilheronia  regalis  Fab.),  about  half  natural  size.      (From 
Felt,  N.  Y.  State  Mus.  Mem.  8.) 


narrow  yellowish  cross  lines.  The  caterpillar  (Fig.  292)  which  feeds  upon  various 
trees,  is  four  or  five  inches  long  when  full-grown  and  has  a  green  body  bearing 
numerous  black  spines  and,  just  back  of  the  head,  a  number  of  very  long  reddish 
spines  bending  backward  and  tipped  with  black.  The  head  is  red.  The  terri- 
fying appearance  of  this  caterpillar  has  probably  been  the  reason  for  calling  it 


FIG.  292. — Full-grown  larva  of  the  Regal  Walnut  Moth,  slightly  less  than  half  natural  size. 
(From  Packard,  Mem.  Nat.  Acad.  Sci.,  IX,  Part  II.) 

"  The  Hickory  Horned  Devil."  The  insect  is  found  from  Massachusetts  to  Loui- 
siana, Texas  and  Missouri,  but  is  not  very  abundant  and  therefore  does  little 
injury.  It  feeds  on  the  black  walnut,  butternut,  hickory  and  a  number  of  other 
trees,  and  has  once  or  twice  caused  some  damage  to  cotton.  It  winters  as  a  pupa 
in  the  ground. 


THE  LEPIDOPTERA 


281 


Another  large  moth  belonging  here  is  the  Imperial  Moth  (Basilona  imperialis 
Dru.,  Fig.  293)  which  has  about  the  same  distribution  as  the  Regal  Walnut  Moth. 
The  adult  often  spreads  six  inches  and  is  yellow,  with  lilac  or  purplish-brown 


FIG.  293. — Imperial  Moth  (Basilona  imperialis  Dru.),  slightly  more  than  half  natural  size. 
(From  Felt,  N.  Y.  State  Mus.  Mem.  8.) 

areas  or  bands  and  spots.  The  caterpillar  (Fig.  294)  is  green  (or  brown  sometimes) , 
from  three  to  four  inches  long  when  full-grown,  rather  well  covered  with  long, 
white  hairs,  and  has  two  pairs  of  rather  stout,  upward  projecting  tubercles  or 
horns  behind  the  head.  It  feeds  on  quite  a  list  of  trees  including  some  of  the 


FIG.  294. — Full-grown    larva    of    Imperial    Moth,    somewhat    reduced.     (Reduced    from 
Packard,  Mem.  Nat.  Acad.  Sci.  IX,  Part  II.) 

evergreens,  and  pupates  in  the  ground  during  the  winter.    Like  the  last  species 
it  is  rarely  if  ever  abundant  enough  to  be  of  economic  importance. 

Several  insects  in  this  family  are  quite  common  at  times  and  locally  may  be 
numerous  enough  to  cause  some  injury  to  oaks,  maples  and  other  trees  they  feed 
upon,  but  their  presence  is  noticed  for  only  a  year  or  two  at  a  time. 


282 


APPLIED  ENTOMOLOGY 


FIG.  295. — Cecropia  Moth  (Samia  cecropiaL.),  slightly  over  half  natural  size.      (Original.) 


FIG.  296. — Polyphemus  Moth  (Telea  polyphemus  Cram.),  about  three-quarters  natural  size. 

(Original.) 


THE  LEPIDOPTERA 


283 


Family  Saturniidae  (The  Giant  Silkworms). — In  this  family  belong  most  of 
the  common,  very  large  moths  found  in  North  America.  Though  their  size 
and  that  of  their  caterpillars  attracts  attention,  these  insects  are  of  little  economic 
importance  as  the  number  of  eggs  laid  by  an  individual  is  not  very  large  and 
they  are  generally  well  scattered  so  that  few  larvae  are  often  found  on  any  one 
tree.  If  the  silk  of  their  cocoons  could  be  utilized  they  would  become  industrially 
important,  but  the  thread  is  frequently  broken  so  that  reeling  it  is  difficult  and 
expensive. 

One  of  the  more  common  species  in  this  family  is  the  Cecropia  Moth  (Samia 
cecropia  L.),  a  very  large,  brownish-gray  insect  (Fig.  295)  with  a  whitish,  crescent- 
shaped  spot  partly  shaded  with  brown,  near  the  center  of  each  wing.  Outside 
this  spot  a  whitish  line  crosses  the  wing  and  the  outer  margin  is  more  or  less 
broken  by  black  spots  on  a  whitish  ground.  The  abdomen  is  brown  with  white 
crossbands.  The  caterpillar  (See  Fig.  21),  which  when  full-grown  is  from  three 


FIG.  297. — Male  Promethea  Moth  (Callosamia  promethea  Dru.),  about  two-thirds  natural 

size.  •    (Original.) 

to  four  inches  long,  is  green  with  tubercles  along  its  back,  two  pairs  near  the 
head  being  coral  red  and  the  others  yellow  except  the  first  and  last  pair  which  are 
blue.  The  insect  feeds  on  many  kinds  of  plants,  including  some  fruit  and  shade- 
trees.  The  moths  appear  in  late  spring,  the  larvae  feed  during  the  summer,  and 
in  the  fall  spin  rather  dense  cocoons  on  the  twigs  of  the  trees,  in  which  they 
pupate  and  pass  the  winter 

A  rather  similar  moth,  though  usually  a  little  smaller,  is  the  Polyphemus 
Moth  (Telea  polyphemus  Cram.),  with  brown  wings  crossed  near  the  outer 
margin  by  a  blackish  band  (Fig.  296).  The  front  wing  has  a  transparent  "eye" 
spot  with  a  yellow  margin,  around  which  is  a  black  line.  The  hind  wing  has  a 
somewhat  similar  spot,  but  the  black  around  it  covers  quite  an  area,  particularly 
toward  the  base  of -the  wing.  The  caterpillar  is  green  with  a  yellow,  oblique 
line  on  the  side  of  most  of  the  segments  of  the  abdomen  and  it  feeds  on  many 
fruit  and  forest  trees.  The  cocoon  is  spun  among  leaves  on  the  ground. 

Somewhat  smaller,  spreading  about  four  inches,  is  the  Promethea  Moth  (Call- 
osamia promethea  Dru.).  The  male  moth  (Fig.  297)  is  dark  brown  except  toward 


284 


APPLIED  ENTOMOLOGY 


the  outer  margin  of  the  wing  where  the  color  lightens  somewhat  outside  a  whitish 
cross  line,  and  the  outer  margin  is  light-grayish  with  fine  brown  lines.  Near 
the  apex  of  the  front  wing  is  a  black  "eye"  spot,  margined  on  the  inner  side  with 
blue.  The  female  (Fig.  298)  is  brown  with  a  triangular,  white  spot  near  the 
center  of  each  wing,  a  short  distance  outside  of  which  the  brown  ends  abruptly 
in  a  very  irregular  edge  against  white  which  shades  off  into  brown  again. 
The  outer  margin  is  as  in  the  male  and  the  eye  spot  is  also  present  on  the 
fore  wing. 

'  The    caterpillar   is  pale    green    with    very  small    black  tubercles    in    pairs 
above,  except   two   pairs   not   far   behind   the   head,  which   are   coral-red  and 
larger  than  the  others,  and  a  yellow  one  above,  near 
the  hinder  end.     The  Iarva3  feed  on  many  kinds  of 
trees  and  shrubs,  appearing  to  prefer  the  sassafras, 
wild  cherry  and  ash,  and  when  through  feeding,  each 
selects  a  leaf,  the  petiole  of  which  it  spins  around, 
fastening  it  in  this  way  to  the  twig  on  which  it 
grew,  so  that  it  cannot  drop  off  in  the  fall.     It  then 


FIG.  298. 


FIG.  299. 


FIG.  298. — Female  Promethea  Moth,  about  two-thirds  natural  size.      (Original.) 
FIG.  299. — Cocoon  of  the  Promethea  Moth,  natural  size.      (From  Britton,   Thirteenth 
Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1913.) 

forms  its  cocoon  with  the  leaf  as  a  partial  wrapping,  drawing  the  edges  around 
the  cocoon  (Fig.  299).  Here,  in  this  hanging  cocoon,  swaying  in  the  winds, 
the  insect  passes  the  winter. 

The  Japanese  Silkworm  Moth  (Philosamia  cynthia  Dru.)  was  introduced 
into  the  United  States  in  a  futile  attempt  to  use  its  cocoons  for  silk.  Some 
of  the  insects  escaped  and  this  species  is  now  occasionally  captured  in  Southern 
New  England  and  the  Middle  Atlantic  States.  The  moth  (Fig.  300)  spreads  about 
six  inches  and  is  of  a  rather  rich  shade  of  brown.  On  each  wing  is  a  large  white 
crescentic  spot,  edged  in  front  by  a  black  line,  and  a  white  band,  shading  on  its 
outer  side  into  lilac,  then  into  brown,  crossing  the  wing,  touches  the  outer  angle 
of  the  crescentic  spot.  On  the  front  wing  a  white  band  runs  from  the  inner 
angle  of  this  spot  to  the  body  and  another  to  the  costa  or  front  margin  of  the 
wing.  On  the  hind  wing  a  similar  band  curves  across  about  halfway  between 


THE  LEPIDOPTKRA 


285 


the  crescent  spot  and  the  base  of  the  wing.  The  caterpillar  feeds  on  the  leaves 
of  the  Ailanthus  tree  and  has  tufts  of  white  hairs  on  its  body.  The  cocoon 
is  made  within  a  partly  rolled  leaf  as  in  the  case  of  the  Promethea  Moth. 

One  of  the  largest  insects  in  this  family  is  known  as  the  Luna  Moth  (Tropcea 
luna  L.).  Its  body  is  densely  covered  with  white  hairs  giving  it  a  woolly  appear- 
ance, and  its  wings  are  pale  green,  with  more  or  less  complete  purplish  margins, 
particularly  strong  along  the  costa  of  the  fore  wing  (Fig.  301).  In  the  front 
wing  is  a  rather  oval  "eye"  spot  connected  by  a  purplish  band  with  the  costa. 
The  hind  wing  also  has  an  "eye"  spot,  more  circular  in  outline,  shaded  with 
darker  on  the  side  nearest  the  body,  and  the  wing  itself  extends  backward  into  a 
long,  narrow  tail.  The  green  caterpillars,  between  two  and  three  inches  long  when 


FIG    300. — Japanese  Silkworm  Moth  (Philosamia  cynthia  Dru.),  about  two-thirds  natural 

size.     (Original.) 


full-grown,  feed  upon  a  number  of  kinds  of  trees  and  pupate  among  leaves  on  the 
ground  in  the  fall.  The  insect  is  found  from  Canada  southward  throughout  the 
United  States  east  of  the  Rocky  Mountains. 

One  of  the  smaller,  very  common  moths  of  this  group  is  the  lo  Moth  (Auto- 
meris  io  Fab.)  which  spreads  between  three  and  four  inches  (Fig.  302).  The  two 
sexes  differ  in  color,  the  ground  color  in  the  male  being  yellow,  while  in  the  fe- 
male that  of  the  fore  wings  is  purplish-red.  The  yellow  of  the  male  fore  wing  has 
irregular  spots  and  a  wavy  line  of  brownish:  in  the  female  the  ground  color  is 
broken  by  irregular  shadings  and  a  lighter  wavy  line.  The  striking  feature  of 
the  hind  wing  in  both  sexes  is  a  large,  circular,  bluish  "eye"  spot  with  a  white 
dot  forward  of  its  center.  The  bluish  shades  into  black  outside,  and  is  surrounded 
by  the  yellow  ground  color.  Between  the  eye  spot  and  the  outer  margins  are  a 
black  line  and  a  dull-rose  band,  and  the  base  and  hinder  margin  are  dull  rose. 


286 


APPLIED  ENTOMOLOGY 


The  caterpillar  is  about  two  inches  long  when  full-grown,  with  a  rather  wide 
reddish-brown  stripe  edged  with  white  below,  on  each  side  of  the  body.  It 
has  many  spines  which  branch,  the  branches  being  tipped  with  black.  Touching 


FIG.  301. — Luna    Moth    (Tropaea   luna  L.),  slightly  over  half  natural  size. 

N.  Y.  State  Mus.  Mem.  8.) 


(From  Felt, 


the  caterpillars  produces  a  nettling  of  the  skin,  due  to  poison  conveyed  through 
the  tips  of  the  spines.  The  larvse  feed  on  fruit,  forest'and  shade-trees  and  usually 
make  their  cocoons  among  leaves  on  the  ground. 


FIG.  302. — Female  Io  Moth  (Automeris  io  Fab.),  about  two-thirds  natural  size. 
Felt,  N.  Y.  State  Mus.  Mem.  8.) 


(From 


There  are  quite  a  number  of  kinds  of  Giant  Silkworms,  the  family  being 
represented  in  all  parts  of  the  country.  One  generation  a  year;  the  moths  appear- 
ing earlier  or  later  in  the  spring  according  to  the  length  of  the  season;  the  larvae 


THE  LEPIDOPTERA 


287 


'feeding  during  the  summer;  and  pupation  in  the  fall,  with  the  winter  spent  in 
this  stage,  appears  to  be  the  general  rule,  though  with  some  exceptions,  for  most 
if  not  all  of  the  species. 

Family  Sphingidse  (The  Hawk  Moths). — This  large  and  widespread 
group  of  insects  has  long  and  rather  narrow  fore  wings  and  its  members 
have  a  strong  flight.  Most  of  them  are  of  quite  large  size  (Fig.  303)  and 
fly  chiefly  at  dusk,  visiting  flowers  for  the  nectar,  upon  which  they  feed. 
They  do  not  alight  on  the  flower  but  hover  over  it,  running  the  tongue, 
which  is  often  much  longer  than  the  body,  into  the  nectary.  The  body 


FIG.  303. — Hawk  Moth  (Sphinx  chersis  Hbn.),  natural  size.     (Original.) 


is  usually  rather  stout,  spindle-shaped,  and  it  and  the  wings  are  often 
beautifully  colored  with  combinations  of  black,  gray,  olive,  tan  and  rose 
or  pink.  The  antennae  are  large,  usually  somewhat  thickened  near  the 
middle,  and  the  end  is  in  some  cases  curved  a  little,  like  a  hook. 

The  larvae  feed  upon  the  leaves  of  various  trees  and  other  plants. 
They  are  naked;  generally  green,  though  frequently  of  other  colors,  and 
in  the  former  case  often  have  oblique  white  streaks  on  the  sides  of  the 
body  and  a  long  horn  projecting  upward  and  backward  from  the  upper 
side  near  the  hinder  end.  Some  when  full-grown,  may  be  two  or  three 
inches  long.  Pupation  is  usually  in  earthen  cells  underground,  though 
some  form  partial  cocoons  of  leaves  and  silk  on  the  surface.  In  some 
species  the  tongue  at  the  time  of  pupation  is  not  enclosed  by  that  part 
of  the  pupal  skin  which  covers  the  body,  but  by  a  separate  portion  which 
joins  the  remainder  at  the  front  of  the  head  and  touches  the  body  about 
halfway  back,  which  makes  it  resemble  the  handle  of  a  pitcher  or  jug 
in  its  relation  to  the  pupa  as  a  whole. 


288 


APPLIED  ENTOMOLOGY 


A  few  species  have  their  wings  only  partially  covered  by  scales. 
These  are  among  the  smaller  species  and  they  fly  during  the  day  (Fig. 
304). 

Of  the  various  species  of  Hawk,  or  Humming  Bird  Moths  as  they  are 
sometimes  called,  only  two  or  three  are  usually 
of  any  great  economic  importance. 

The  Tobacco  and  Tomato  Worms.— There 
are  ^wo  c^ose^y  related  Hawk  Moths  whose 
larvae  feed  on  tobacco  and  tomato  leaves. 
One  of  these  is  known  as  the  Northern 
Tobacco  (or  Tomato)  Worm  (Phlegethontius 
quinquemaculata  Haw.)  and  the  other  as  the 
Southern  Tobacco  Worm  (Phlegethontius  sexta 
Johan.).  The  former  is  present  nearly  every- 
where in  the  United  States:  the  latter  from 
Massachusetts  southward,  and  westward  to 
the  Pacific  Coast. 

The  adult  is  a  moth  (Fig.  305)  spreading  from  four  to  five  inches, 
but  in  the  Northern  Tobacco  Worm  the  color  of  the  fore  wings  is  ashy- 
gray  and  the  abdomen  has  a  row  of  yellow  spots,  usually  five  in  number 


FIG.  304. — Day-flying  Hawk 
Moth  (Hemaris  diffinis  Bdv.), 
about  natural  size.  (Original.) 


FIG.  305. — Northern  Tobacco  Worm  Moth  (Phlegethontius  quinquenaculata  Haw.),  natural 
size.     (From  Bntton,  Sixth  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1906.) 

on  each  side,  while  in  the  Southern  Tobacco  Worm  the  fore  wings  are 
brownish-gray  and  there  are  usually  six  yellow  spots  on  each  side  of  the 
abdomen. 


THE  LEPIDOPTERA 


289 


The  life  history  in  both  species  is  quite  similar.     Winter  is  passed 
as  a  pupa  (Fig.  306)  iii  the  ground  and  in  these  insects  the  tongue 


FIG.  306. — Pupa  of  the  Southern  Tobacco  Worm  (left)  and  of  the  Northern  Tobacco 
Worm  (right),  natural  size.  Note  difference  in  length  of  the  tongue  case.  (From 
Britton,  Sixth  Kept.  Ent.  Conn.  Agr.  Exp.  Sta.  1906.) 


FIG.  307. — Full-grown  larva  of  Southern  Tobacco  Worm,  natural  size.     (From  Britton, 
Sixth  Kept.  Ent.  Conn.  Agr.  Exp.  Sta.  1906.) 

has  a   separate  case  in  the  pupa.     The  moths   appear  in    the  spring 
and  lay  their  eggs  singly  on  the  leaves  of  their  food  plants,  and  the 


19 


290 


APPLIED  ENTOMOLOGY 


caterpillars  feed  for  3  or  4  weeks,  becoming  three  or  four  inches  long, 
green  or  sometimes  brown  in  color.  In  the  Northern  Tobacco  Worm 
each  abdominal  segment  is  marked  on  the  side  by  an  oblique  greenish-white 
stripe  joining  a  similar  horizontal  one  at  its  lower  end,  forming  a  series 
of  whitish  Vs.  On  the  hinder  end  of  the  body  above,  is  a  projecting 
green  horn  with  black  sides.  The  larva  of  the  Southern  Tobacco  Worm 
(Fig.  307)  has  only  the  oblique  bands  and  the  horn  is  usually  reddish. 
In  the  northern  part  of  the  range  of  these  species  there  is  one  generation 
a  year.  Farther  south,  two  seems  to  be  the  rule,  while  in  the  Gulf 
States  three  or  four  are  claimed  to  occur. 

Control. — Hand  picking  is  a  frequent  method  of  control  where  the 
larvae  are  not  abundant.  Spraying  when  the  caterpillars  are  first  seen, 
with  arsenate  of  lead,  standard  formula,  has  proved  effective.  Applied 
as  a  dust  it  has  also  given  good  results,  but  this  material  either  as  a  spray 
or  as  a  powder  should  not  be  used  on  tomatoes  after  the  fruit  is  half 
grown. 

The  remaining  families  of  Lepidoptera  to  consider  are  those  of  the 
suborder  Rhopalocera,  or  butterflies.  Most  of  the  insects  in  this  section 
are  rarely  of  much  economic  importance,  their  larvae  feeding  chiefly  on 
plants  not  utilized  in  any  way  as  food.  Occasionally  some  species  may 
cause  local  injury,  but  only  a  few  need  special  consideration  from  this 
standpoint. 


FIG.  308.  FIG.  309. 

FIG.  308. — Skipper  Butterfly  (Epargyreus  tityrus  Fab.),  natural  size.      (Original.) 
FIG.  309. — Little   Copper    Butterfly    (Heodes    hypophleas    Bdv.),    about   natural   size. 
(Original.) 

Family  Hesperiidae  (The  Skippers). — These  are  rather  small  butterflies 
which  have  a  curious  " skipping"  style  of  flight.  They  are  most  frequently 
black,  or  yellow  and  black  in  color,  often  with  silvery  spots  or  streaks  (Fig.  308). 
The  larvae  in  this  family  have  heads  much  larger  than  the  part  of  the  body  next 
behind,  making  them  easy  to  recognize.  One  of  the  larger  members  of  this 
group,  found  in  the  South  feeds  as  a  caterpillar  on  the  bean,  and  is  known  as  the 
Bean  Leaf-roller. 

Family  Lycaenidae. — In  this  group  belong  the  little  blue  butterflies  spreading 
in  most  cases  at  least,  less  than  an  inch;  similar  sized  dark-brown  butterflies;  and 
others  which  are  of  a  red  or  coppery  color  (Fig.  309),  with  black  spots.  Many 


THE  LEPIDOPTERA  .     291 

of  these  insects  are  very  common  but  are  of  no  importance  economically.  One 
species  here  departs  from  the  general  rule  as  to  the  food  of  Lepidoptera,  its  larva 
being  carnivorous  and  feeding  on  plant  lice.  Unfortunately  it  is  not  common 
enough  to  be  very  beneficial. 

Some  of  the  species  in  this  family  have  more  than  one  generation  each  year 
and  the  adults  of  the  two  generations  are  so  different  that  until  one  kind  was 
bred  from  eggs  laid  by  the  other  they  were  supposed  to  be  different  species. 
Difference  in  color,  markings  or  both,  may  therefore  be  correlated  with  the  season 
of  the  year,  and  insects  having  two  different  forms  according  to  the  season, 
present  cases  of  what  is  called  seasonal  dimorphism. 


FIG.  310. — The  Monarch  (Danaus  archippus  Fab.),  natural  size.      (Original.) 

Family  Danaidae. — This  small  family  is  of  interest  in  the  United 
States  mainly  because  it  includes  one  of  our  largest  and  widely  distributed 
butterflies,  the  Monarch  (Danaus  archippus  Fab.).  This  is  common 
in  nearly  all  parts  of  the  country  and  has  a  striking  way  of  sailing  about 
in  the  air.  The  ground  color  of  the  wings  is  tawny  brown  marked 
with  black  lines  along  the  veins,  and  broad  black  borders  containing 
white  spots  (Fig.  310).  The  caterpillars  feed  upon  milkweed  and  are 
greenish-yellow  with  black  cross-bands  and  a  pair  of  soft,  fleshy  projec- 
tions on  the  back  a  little  behind  the  head,  and  another  pair  not  far  from 
the  hinder  end  of  the  body.  The  pupa  (chrysalis)  is  usually  attached  to 
the  plant  and  is  about  an  inch  long,  stout,  bright  green  with  golden  dots. 

Though  the  Monarch  breeds  in  the  Northern  States  during  the 
summer,  it  appears  to  come  from  the  South  each  spring,  and  in  the  fall 
multitudes  often  gather  and  fly  southward  together.  Whether  they 


292 


APPLIED  ENTOMOLOGY 


succeed  in  reaching  climates  where  they  can  successfully  winter  is  perhaps 
questionable,  but  if  not,  others  at  least,  make  their  way  North  each 
spring. 

This  insect  is  practically  free  from  attack  by  birds,  probably  because 
it  is  able  to  produce  a  disagreeable  odor. 

Family  Nymphalidse. — This  large  family  includes  many  familiar 
forms,  most  of  them  large  or  of  at  least  fair  size.  Their  fore  legs  have 
been  reduced  so  much  they  they  are  no  longer  used  but  are  carried 
folded  up  against  the  thorax. 

Several  of  the  common  species  in  this  group  are  found  in  Europe 
as  well  as  in  this  country  and  a  few  occur  nearly  everywhere  in  the 
world  where  food  and  temperature  permit  their  existence.  The  larvae 
of  some  species  feed  on  the  currant,  gooseberry  and  hop  in  the  list  of 
cultivated  plants,  but  are  not  often  important  pests. 


FIG.  311. — The  Viceroy  (Basilarchia  archippus  Cram.),  natural  size.      (Original.) 

In  one  section  of  the  family  the  insects  are  usually  black  with  blue 
or  green,  and  occasionally  red  spots,  and  one  or  two  species  have  a  white 
band  across  the  wings.  One  of  this  group,  however,  differs  greatly  in 
color  from  all  the  rest  of  its  relatives,  being  reddish-brown  with  black- 
lined  veins,  black  wing  borders  enclosing  white  spots,  and  so  closely 
resembling  the  Monarch  that  it  has  been  called  the  Viceroy  (Fig.  311) 
It  differs  from  the  Monarch,  to  the  eye,  however,  by  the  presence  of 
a  narrow  black  band  across  the  hind  wings  and  by  its  somewhat  smaller 
size. 

This  radical  departure  in  color  and  pattern  of  this  insect  from  that 
of  all  its  near  relatives  is  believed  to  be  because  this  group  is  one  freely 
attacked  by  birds  for  food,  while  the  Monarch,  perhaps  because  of  a 
disagreeable  odor,  escapes.  Any  imitation  which  would  deceive  the 
birds,  would  accordingly  protect  insects  possessing  it  and  enable  them 


THE  LEPIDOPTERA 


293 


to  avoid  destruction.  How  such  a  change  could  be  rapidly  developed, 
however,  to  such  a  degree  as  to  enable  its  possessors  to  benefit  by  it, 
has  not  been  satisfactorily  explained,  and  if  it  were  not  so  developed 
the  individuals  in  which  the  change  began  could  hardly  differ  enough 
from  their  former  condition  to  escape.  Here  remains  one  of  the  unsolved 
problems  of  insect  life. 

Family  Satyridae  (The  Satyrs). — The  insects  belonging  in  this  family  are  of 
medium  size,  and  nearly  all  have  gray  or  brown  wings  with  spots  more  or  less 
resembling  eye  spots  (Fig.  312) .  They  are  common  near  the  edges  of  woods  and 
sometimes  drift  out  into  the  fields.  One  species  is  found  only  on  the  tops  of  the 
White  Mountains  in  New  Hampshire  and  on  the  higher  Rocky  Mountains. 
How  these  colonies  became  so  widely  separated  is  a  question,  though  explanations 
for  it  have  been  suggested. 


FIG.  312. — Satyr  Butterfly  (Cercyonis  alope  Fab.),  naturalvsize.     (Original.) 

Family  Pieridae. — In  this  family  belong  the  medium  sized  or  small 
yellow  butterflies  of  various  shades  and  the  white  ones,  common  in  all 
parts  of  the  country.  About  50  kinds  occur  in  the  United  States  and 
some  of  them  are  occasionally,  and  others  almost  always,  injuriously 
abundant  in  one  place  or  another. 

The  Imported  Cabbage  Butterfly  (Pontia  rapes  L.). — This  insect,  a 
native  of  Europe,  appears  to  have  reached  Quebec  about  1859.  It  spread 
rapidly  and  ten  years  later  had  reached  Massachusetts.  Other  specimens 
arriving  at  New  York  and  Charleston,  N.  C.,  also  established  centers 
from  which  the  insect  spread  in  all  directions,  and  it  is  now  found  nearly 
everywhere  in  the  United  States. 

The  adult  (Fig.  313a)  spreads  a  little  less  than  two  inches.  Its  wings 
are  white,  the  tip  of  the  front  wing  grayish.  In  the  male  there  is  a  black 
spot  near  the  center  of  the  front  wing  and  one  on  the  front  margin  of 
the  hind  wing,  while  in  the  female  the  front  wing  has  a  second  black 
spot  behind  the  other. 


294 


APPLIED  ENTOMOLOGY 


The  insect  passes  the  winter  as  a  pale  brown  chrysalis  (Fig.  313d) 
about  three-quarters  of  an  inch  long,  attached  in  some  protected  place. 
The  adults  emerge  in  the  spring  and  lay  their  eggs  singly  (Fig.  3136) 
on  the  leaves  of  cabbage,  cauliflower,  mustard,  nasturtium  and  other 
plants  of  the  family  Cruciferse,  and  about  a  week  later  the  caterpillar 
hatches  and  begins  to  feed.  At  first  it  is  pale  green,  but  when  full- 
grown,  after  about  2  or  3  weeks,  is  a  soft,  velvety-green,  and  about  an 
inch  long  (Fig.  313c).  At  first  it  feeds  on  the  under  surface  of  the 


FIG.  313. — Cabbage  Butterfly  (Pontia  rapce  L.):  a,  adult,  slightly  enlarged;  b,  egg, 
from  side  and  from  above,  considerably  enlarged;  c,  caterpillar,  somewhat  enlarged;  d, 
chrysalis,  somewhat  enlarged.  (From  U.  S.  D.  A.  Farm.  Bull.  856.) 

leaf,  but  after  growing,  eats  holes  through  and  may  leave  only  the  veins. 
It  often  bores  into  the  forming  heads  also,  in  search  of  more  tender  food. 
It  feeds  for  from  2  to  3  weeks,  then  .pupates  for  a  rather  shorter  period, 
at  the  end  of  which  time  the  adult  emerges  and  lays  eggs  for  a  second 
generation.  There  are  usually  two  or  three  generations  in  the  Northern 
States  and  as  many  as  five  or  six  in  the  South. 

Where  these  insects  are  abundant  they  cause  considerable  injury, 
not  only  to  the  leaves  but  by  boring  into  the  heads,  reducing  their  value. 

Control. — Spraying  with  a  stomach  poison,  preferably  arsenate  of 
lead,  a  little  stronger  than  the  standard  formula,  as  soon  as  the  cater- 
pillars appear  in  the  spring,  is  a  successful  treatment,  but  as  the  spray 
tends  to  run  off  the  smooth  leaves  of  the  plants,  the  addition  of  a  little 
soap  as  a  " sticker"  is  desirable.  If  the  larvae  of  the  first  generation 
are  killed  for  the  most  part  by  this,  later  applications  will  generally  prove 
unnecessary.  In  some  cases  the  poison  is  dusted  on  instead  of  sprayed. 


THE  LEPIDOPTERA 


295 


If  treatment  is  needed  after  the  heads  are  half  grown,  they  may 
be  dusted  with  pyrethrum,  though  the  danger  of  poisoning  them  by  the 
use  of  arsenate  of  lead  is  practically  none. 

A  native  cabbage  butterfly  closely  resembling  the  last,  was  formerly 
common  in  the  North,  but  appears  to  have  suffered  from  competition 
with  its  imported  rival.  A  southern  native  species  has  also  become 
somewhat  reduced  in  abundance,  but  less  so  than  the  northern  one. 


r 


FIG.  314. — Male   Sulfur  or  Yellow   Butterfly    (Eurymus   philodice  Godt.),   natural  size. 

(Original.} 

The  common  sulfur-yellow  butterflies  (Fig.  314)  with  more  or  less  of  black 
markings  on  their  wings  are  for  the  most  part,  feeders  on  clover  in  their  larval 
stages.  One  of  them,  the  Alfalfa  Caterpillar  (Eurymus  eurytheme  Boisd.)  is 
frequently  a  pest  on  alfalfa.  It  occurs  everywhere  in  the  United  States  west  of 


FIG.  315.  —  Alfalfa  Butterfly  (Eurymus  eurytheme  Boisd.),  about 

(From  U.  S.  D.  A.  Bull.  124.) 


times  natural  size. 


the  Allegheny  Mountains  and  has  been  taken  occasionally  along  the  Atlantic 
Coast,  but  is  chiefly  of  importance  in  the  Southwest. 

The  adult  (Fig.  315)  spreads  about  two  inches  and  its  wings  are  orange- 
yellow  with  black  outer  borders;  a  black  spot  in  front  of  the  center  of  the  fore 
wing  and  two  reddish-orange  spots  which  touch  each  other,  near  the  center  of 


296  APPLIED  ENTOMOLOGY 

each  hind  wing.  In  the  female  the  black  wing  border  has  yellow  spots  in  it. 
Sometimes  the  orange  color  in  the  female  is  replaced  by  whitish.  The  cater- 
pillar is  brown  at  first  but  later  becomes  dark-green  with  a  white  stripe  on  each 
side  (Fig.  316).  Alfalfa,  clovers,  vetches  and  other  legumes  are  fed  upon. 
The  number  of  generations  seems  to  vary  in  different  parts  of  the  country 
from  two  in  the  North  to  six  or  possibly  more,  in  the  far  South.  The  colder,  or 


FIG.  316. — Caterpillar  of  the  Alfalfa  Butterfly,  about  three  times  natural  size.      (From  U. 

S.  D.  A.  Bull.  124.) 

in  the  Southwest,  the  dry  months  may  be  passed  either  as  larva,  pupa  or  adult. 
Treatment  is  by  cultural  methods  such  as  pasturage,  or  early  and  close  cutting  of 
the  crop,  followed  if  necessary  by  rolling  or  brush  dragging. 

The  spreading  of  an  insect  introduced  into  a  country  is  always  of 
interest,  even  if  no  financial  factor  is  involved,  and  several  of  the  species 
considered  in  this  chapter  supply  good  examples  of  this.  Its  method  of 
introduction;  its  establishment;  the  rapidity  with  which  it  spreads,  and 
the  final  limits  of  its  distribution,  are  all  topics  for  investigation. 

In  the  case  of  the  Gypsy  Moth  its  introduction  was  apparently  inten- 
tional, though  it  was  far  from  the  plan  of  the  scientist  who  brought  it  to 
this  country  that  it  should  escape.  It  is  stated  that  this  scientist  had  in 
mind  testing  the  silk-producing  possibilities  of  various  Lepidoptera  and 
imported  a  number  of  species  for  that  purpose.  Unfortunately  in  some 
way,  some  of  the  Gypsy  Moth  specimens  escaped  and  as  he  could  not 
find  them,  he  issued  a  notice  calling  attention  to  the  fact,  and  warning 
the  public  of  the  possible  menace  they  might  become. 

The  Brown-tail  Moth  appears  to  have  been  brought  to  this  country 
as  a  winter  tent  containing  young  caterpillars,  on  an  importation  of 
roses  from  Europe.  This  occured  before  the  inspection  of  nursery  stock 
imported  into  this  country  was  required  by  law.  How  the  Cabbage 
Butterfly  arrived,  is  not  known,  but  it  was  probably  the  chrysalis  on 
some  material  brought  as  freight. 

It  is  evident  that  in  any  case,  either  an  adult  female  able  to  deposit 
fertile  eggs,  or  else  several  individuals  at  least,  in  some  early  stage, 
must  be  imported  at  about  the  same  time,  if  the  species  is  to  obtain  a 
start.  Then  with  an  individual  ready  to  lay  its  eggs,  suitable  food 


THE  LEPIDOPTERA  297 

plants  for  its  young  must  be  found.  There  can  be  no  doubt,  in  theory 
at  least,  that  there  have  been  many  cases  in  the  past  where  failure  to 
succeed  in  this  has  resulted  in  the  failure  to  establish  themselves,  of 
many  species  which  would  have  been  serious  pests. 

Once  started,  however,  even  in  a  small  way,  an  increase  in  numbers 
and  in  distribution  becomes  possible.  If  some  of  the  insects,  however, 
were  parasitized  and  the  parasites  escaped,  as  well  as  those  not  so  affected, 
the  spread  might  be  checked  because  of  the  small  number  of  the  pests 
which  would  not  be  found  by  the  parasites. 

The  spreading  of  a  species  from  the  point  where  it  starts,  has  been 
aptly  compared  to  that  of  a  ripple  caused  by  throwing  a  stone  into  water, 
which  passes  out  in  every  direction  on  its  surface.  Such  a  spread  will 
extend  as  far  as  the  insect  can  find  food  on  which  it  can  live  and  a  tem- 
perature and  humidity  under  which  it  can  survive.  It  follows  that  for 
many  insects  adapted  to  northern  climatic  conditions,  a  point  will  be 
reached  in  its  southward  spread  where  the  temperature  and  humidity  are 
such  as  to  prevent  its  going  farther.  A  lofty  and  continuous  mountain 
range  may,  by  producing  such  conditions,  also  prove  a  barrier  to  farther 
extension  in  that  direction,  even  though  beyond  the  range  a  favorable 
climate  may  again  be  found.  Absence  of  any  food  upon  which  an  insect 
can  live  will  also  put  an  end  to  distribution  in  that  direction,  and  a  pest 
adapted  to  the  moist  climate  of  the  Eastern  States  may  find  itself  unable 
to  establish  itself  in  arid  regions.  The  rapidity  with  which  it  spreads 
appears  to  be  determined  by  its  fecundity,  power  of  flight  in  many  cases, 
and  food  supply,  at  least  generally;  an  insect  having  a  high  rate  of  in- 
crease, abundant  food,  and  strong  in  flight  sometimes  spreading  several 
hundred  miles  in  a  year.  The  much  larger  area  to  the  north  and  north- 
east of  Boston  than  to  the  south  and  west,  now  occupied  by  the  Brown- 
tail  Moth  appears  to  be  due,  in  part  at  least,  to  strong  southwesterly 
winds  while  the  moths  are  flying. 

Study  of  these  and  other  factors  involved,  shows  that  northern  insects 
as  they  spread  southward  are  found  chiefly  at  least,  on  higher  land.  One 
living  at  near  the  sea  level  in  the  Northern  States  will  generally  be  found 
in  the  mountains  in  the  South,  and  if  it  extends  into  Mexico  it  will  there 
occur  only  on  the  higher  Cordilleras,  gaining  by  its  elevation  the  lower 
temperature  it  has  lost  by  its  change  of  latitude. 

Thus  we  find  that  with  sufficient  information  at  hand,  the  distribution 
of  many  insects  can  be  mapped,  and  that  there  is  a  division  of  the  country 
into  regions,  the  insects  of  one  region  rarely  spreading  far  beyond  its 
limits,  and  then  only  forming  outposts  of  the  species. 

It  is  true  that  some  species  are  less  affected  than  others  by  these 
conditions.  The  Monarch  Butterfly,  the  House  Fly  and  many  others 
appear  to  be  able  to  live  under  wide  differences  of  temperature,  humidity 
and  the  other  factors  concerned.  As  a  whole  though,  an  insect  will 


298 


APPLIED  ENTOMOLOGY 


spread  within  certain  limits,  but  only  within  these,  and  this  applies  to 
other  animals  and  to  plants  as  well. 


Family  Papilionidae  (The  Swallow-tails). — The  butterflies  of  this 
group  are  nearly  all  large,  and  with  a  backward-projecting  lobe  or 
tail  on  the  hind  wing.  One  species  or  another  may  be  seen  in  almost 
every  part  of  the  country  but  they  rarely  do  much  injury,  feeding  for  the 
most  part  on  plants  of  little  importance.  The  Black  Swallow-tail 
Butterfly  (Papilio  polyxenes  Fab.)  is  probably  the  most  important  species, 
as  it  occurs  all  over  the  United  States  and  feeds  on  celery,  carrots,  par- 
snips and  other  plants. 


FIG.  317. — Celery  Butterfly  (Papilio  polyxenes  Fab.):  a,  full-grown  caterpillar;  b, 
head  of  same  showing  osmaterium  extended;  c,  male  butterfly;  d,  outline  of  egg;  e,  young 
larva;  /,  chrysalis.  All  about  natural  size  except  d,  which  is  much  enlarged.  (From  U. 
S.  D.  A.  Farm.  Bull  856.) 


The  butterfly  (Fig.  317c)  spreads  between  three  and  four  inches,  and 
its  wings  are  black  with  two  rows  of  yellow  spots  crossing  each  wing,  with 
blue  shadings  between  the  two  rows  on  the  hind  pair.  There  is  also  a 
black  spot  surrounded  by  orange  on  the  outer  part  of  the  hinder  margin 
of  the  hind  pair.  In  the  male  the  inner  row  of  yellow  spots  becomes  a 
band  on  the  hind  wing. 

In  the  South  the  butterflies  winter  over,  but  in  the  North  this  period  is 
spent  as  the  pupa.  Eggs  are  laid  singly  on  the  leaves  of  the  food  plants, 
and  hatch  in  about  10  days.  The  caterpillars  feed  for  from  10  days  to 
several  weeks,  then  form  their  chrysalids  (pupae)  on  some  part  of  the  plant 
(Fig.  317f)  and  in  from  ten  days  to  2  weeks  more  the  adult  butterflies 
emerge.  There  are  two  generations  in  the  North  and  more  in  the  South. 


THE  LEPIDOPTERA  299 

The  caterpillar  when  full-grown  (Fig.  31  la  and  6)  is  about  two  inches 
long,  green  with  a  black  cross  band  on  each  segment,  which  may  enclose  six 
yellow  spots  or  may  fail  to  close  these  in  on  the  front  side  of  the  band. 
Just  back  of  the  head  is  an  opening  out  of  which  a  soft,  widely  forked 
horn  can  be  protruded  when  the  insect  is  distributed.  Such  structures 
are  called  osmeteria  and  give  off  a  disagreeable,  pungent  odor,  and  are 
probably  to  drive  away  enemies  which  may  attack  them. 

This  insect  is  rarely  if  ever  important  enough  to  call  for  any  control 
other  than  destroying  the  larvae  by  hand,  though  in  most  cases  spraying 
with  a  stomach  poison  would  be  entirely  effective  if  such  a  treatment  were 
needed. 

A  similar  species  present  on  the  Pacific  Coast,  has  the  same  habits. 


CHAPTER  XXX 


THE  MECOPTERA 

The  Mecoptera  is  a  small  order  of  insects,  both  in  numbers  and  in  the 
size  of  its  members.  The  adults  usually  have  wings  which  are  mem- 
branous, long,  and  generally  narrow,  with  numerous  veins.  In  a  few 
cases,  however,  they  are  reduced  or  even  rudimentary.  The  head  is 
elongated  on  its  underside,  forming  a  sort  of  beak  or  rostrum,  at  the  end 
of  which  are  the  chewing  mouth  parts  (Fig.  318).  In  the  males  of  one 
genus  the  terminal  segments  of  the  abdomen  are  drawn  out  and  curl  up- 
ward, suggesting  the  position  of  the  end  of  the  body  in  the  scorpion,  and 
from  this  the  common  name  ''Scorpion  Flies"  has  been  applied  to  the 

order,  though  some  of  its  members  do  not 
have  this  character.  The  larvae  considerably 
resemble  small  caterpillars. 

The  distinctive  characters  of  the  order 
are: 

Insects  which  when  adult  nearly  always 
have  four  membranous  wings,  long  and  narrow 
and  with  numerous  veins:  head  prolonged 
downward  forming  a  beak,  bearing  chewing 
mouth  parts  at  its  end.  Larvce  more  or  less 
caterpillar-like.  Metamorphosis  complete. 

Mecoptera  occur  in  nearly  all  parts  of  the 
world  but  nowhere  appear  to  be  very  abundant. 
They  seem  to  prefer  to  live  in  places  having  rank 

growth,  and  in  low,  damp  woods,  and  are  apparently  carnivorous  both 
as  larvae  and  adults.  A  few  species  are  found  on  snow  during  the  winter 
months  and  are  wingless  or  nearly  so,  but  most  of  the  group  have  wings 
longer  than  their  bodies  and  fly  quite  well.  The  eggs  are  usually  laid 
in  masses  in  the  ground  and  the  larvae  live  in  burrows  in  the  ground, 
coming  out  to  feed.  They  have  legs  supporting  the  abdomen  and  these 
are  more  numerous  than  in  caterpillars.  As  far  as  known  they  pupate  in 
earthen  cells  in  the  ground. 

The  adults  certainly  feed  upon  other  insects:  larvse  in  confinement 
can  be  fed  upon  meat,  but  their  natural  food  is  probably  any  animal 
material  they  can  obtain.  Under  such  circumstances,  these  insects 
must  be  regarded  as  being,  at  best,  of  little  economic  importance.  Fossil 
forms  belonging  to  the  Mecoptera  have  been  discovered  in  different  parts 
of  the  world. 

In  a  general  way  this  order  appears  to  have  the  Diptera,  Trichop- 
tera  and  Lepidoptera  as  its  nearest  relatives. 

300 


FIG.  318.— Adult  Meeopteron 
(Panorpa  nuptialis  G  e  r  s  t . ) 
natural  size,  showing  beak  pro- 
jecting downward  from  the 
head,  on  the  end  of  which  are 
the  mouth  parts.  (Original.) 


CHAPTER  XXXI 
THE  DIPTERA 

The  Diptera  or  Flies  are  small  insects,  the  largest  species  known  being 
slightly  more  than  two  inches  long,  but  the  majority  are  much  smaller, 
and  many  are  almost  microscopic.  The  flies  as  a  group  are  distinguished 
from  other  insects  by  the  presence  of  only  one — the  front — pair  of  wings, 
attached  to  the  mesothorax.  Sometimes  these  are  absent,  the  insect 
being  entirely  wingless,  but  there  are  only  a  few  such  cases.  The  hind 
wings  have  been  transformed  into  a  pair  of  curious  structures  known  as 
halteres.  They  are  small  and  each  resembles  a  sort  of  knob  joined  to  the 
body  by  a  stalk,  usually  slender,  and  variable  in  length.  They  are 
believed  to  have  special  functions  but  what  these  are  is  far  from  settled. 

The  wings  are  usually  transparent  though  sometimes  smoky  or  other- 
wise colored,  and  in  some  instances  scales  are  present  either  along  the 
veins  or  elsewhere,  and  in  one  family  they  entirely  cover  both  the  body 
and  wings.  The  veins  are  usually  quite  numerous  but  often  show  a 
tendency  to  unite  toward  the  outer  margin  of  the  wing,  forming  closed 
cells  in  this  way  as  well  as  by  the  more  usual  method  with  cross  veins. 
In  some  families,  the  veins  are  very  few  and  sometimes  several  appear 
only  as  faint  traces.  The  hinder  margin  of  the  wing  not  far  from  its 
attachment  to  the  body  frequently  has  a  notch  called  the  axillary  incision 
or  sinus,  and  the  membrane  from  here  to  the  base  may  form  one  lobe, 
or  by  other  incisions  consist  of  two  or  even  three  lobes.  The  one  nearest 
the  base  in  some  instances  appears  to  become  enlarged  and  lie  over  the 
base  of  the  halter,  often  partly  or  entirely  concealing  this  structure  from 
above. 

The  head  of  the  fly  is  connected  with  the  thorax  by  a  small  neck  which 
permits  considerable  rotation.  Much  of  its  surface  is  occupied  by  the 
very  large  compound  eyes  which  frequently  meet  above,  particularly  in 
the  males.  Between  the  two  eyes,  or  behind  their  point  of  meeting, 
are  usually  three  ocelli  on  the  top  of  the  head. 

The  antennae  vary  greatly.  They  may  consist  of  as  many  as  16 
segments  or  as  few  as  three,  in  the  latter  case  a  bristle,  frequently  feathered, 
being  often  present,  joined  to  the  outer  segment. 

In  one  section,  a  crescent-shaped  cleft  occurs  above  the  attachment 
of  the  antennas  to  the  head,  curving  downward  on  each  side.  This  slit 
is  called  the  lunula,  and  at  the  time  when  the  fly  escapes  from  its  pupa 
case  a  large,  bladder-shaped  structure  is  pushed  out  through  this  from 
the  inside  of  the  head,  and  pressing  against  the  end  of  the  case,  forces  it 
oft7,  enabling  the  fly  to  escape.  Later,  this  structure  which  is  called  the 
ptilinum  is  drawn  back  into  the  head. 

301 


302 


APPLIED  ENTOMOLOGY 


The  mouth  parts  of  flies  are  for  sucking,  and  in  some  cases  for  piercing, 
also.  True  " biting  flies"  do  not  exist,  the  "bite"  being  really  caused  by 
the  plunging  of  the  sharp-ended,  piercing  mouth  parts  into  the  object 
attacked.  There  seems  to  be  little  doubt  that  the  mouth  parts  of  flies  have 
been  derived  from  ancestors  with  chewing  structures,  but  the  changes 
have  been  so  great  that  to  identify  the  different  pieces  with  the  corre- 
sponding ones  of  chewing  insects  is  very  difficult,  and  different  views  on 
this  have  been  advanced  by  students  of  the  subject. 


FIG.  319. — Mouth  parts  of  A,  a  Tabanid;  B,  a  mosquito:  a,  antenna;  au,  compound 
eye;  hp,  hypopharynx;  Ibr,  labrum;  md,  mandible;  mx,  maxilla;  mx2,  labium;  oc,  ocellus; 
pm,  maxillary  palpus.  (Modified  from  Laug's  Lehrbuch.) 

Without  going  into  details,  it  may  be  stated  that  in  the  more  typical 
fly  mouth  parts  there  are  six  bristle-shaped  structures  enclosed  by  a 
sheath,  and  one  pair  of  segmented  palpi  (Fig.  319).  The  sheath  is 
generally  regarded  as  representing  the  labium  or  hinder  lip,  while  the 
bristles  represent  the  front  lip  or  labrum,  the  tongue  or  hypopharynx, 
the  two  mandibles  and  the  two  maxillae.  At  the  outer  end  of  the  sheath 
is  a  pair  of  lobes,  often  large,  and  these  are  considered  as  the  labial 
palpi,  leaving  the  segmented  pair  to  represent  the  maxillary  palpi. 
In  some  cases,  the  surfaces  of  the  lobes  regarded  as  labial  palpi  are 
roughened  and  adapted  to  the  rasping  of  surfaces.  Bringing  together 
certain  of  the  bristle-like  mouth  parts  forms  two  tubes,  or,  in  some  cases, 
grooves  more  or  less  completely  closed,  through  which  fluids  can  be 
drawn  into  the  body,  and  saliva  be  led  into  the  wound  made  by  the 
tips  of  the  bristles.  Solid  food  is  utilized  only  by  first  dissolving  it  in 
saliva. 


THE  DIPTERA  303 

The  thorax,  though  composed  of  three  segments  as  usual,  has  these 
very  closely  and  firmly  united.  In  the  abdomen,  the  number  of  visible 
segments  varies  from  nine  to  five,  or  even  four  in  some  instances.  The 
legs,  usually  at  least,  are  well  developed,  with  a  pair  of  claws  at  the  tip 
and  a  pulvillus  at  the  base  of  each  claw.  Between  the  claws  there  is 
often  an  membranous  pad,  similar  to  a  pulvillus,  or  it  may  be  a  bristle. 
In  either  case,  this  centrally  placed  structure  is  called  an  empodium. 

On  the  surface  of  the  body,  bristles  are  often  present  which  have 
definite  positions  and  are  of  aid  in  identifying  the  species. 

Fly  larvae  are  usually  called  maggots.  Some  have  well  developed 
heads  while  in  others  no  structure  of  this  nature  can  be  recognized. 
True  legs  appear  to  be  absent,  though  projections  of  the  body  which  can 
be  utilized  in  moving  about  are  common  and  often  bear  circlets  of  hooks. 
These  vary  in  their  position  in  different  species.  The  larvae  breathe 
through  spiracles,  but  the  location  of  these  differs  greatly.  In  some  they 
are  found  along  the  sides  of  the  body  as  usual;  in  others  there  is  a  pair 
near  each  end  of  the  body;  in  still  others  there  is  only  one  pair  at  the 
hinder  end,  and  these  may  occur  at  the  tip  of  a  very  extensible  tube 
which,  when  fully  stretched  out,  may  be  several  inches  long.  Nourish- 
ment is  sometimes  obtained  by  osmosis  directly  through  the  body  wall 
of  the  larva  but  it  is  generally  taken  into  the  mouth.  The  mouth  parts 
in  the  least  modified  forms  are  of  the  chewing  type  but  in  most  members 
of  the  order  they  are  greatly  modified.  In  some  cases,  a  pair  of  claws  or 
hooks  appear  to  be  the  only  structures,  while  in  others  a  chitinous  "rake" 
consisting  of  a  cross-bar  bearing  a  row  of  teeth  and  connected  with  a 
single  rod  running  backward,  serves  to  rasp  and  break  open  the  vegetable 
cell  walls  and  expose  their  fluid  or  semifluid  contents  of  which  the  larva 
avails  itself. 

Some  flies  construct  regular  cocoons  but  the  pupa  is  usually  either 
naked  or  located  in  a  puparium  which  is  the  last  larval  skin.  In  this 
case,  the  larva,  when  ready  to  pupate,  shrinks  away  from  its  skin  and 
pupates  within  it,  using  this  skin  or  puparium  as  a  protection  instead 
of  making  a  cocoon.  Escape  from  the  puparium  may  be  either  through 
a  T-shaped  split  on  the  back  near  the  front  end;  a  transverse  split 
between  the  eighth  and  ninth  abdominal  segments  in  a  few  cases;  or 
through  a  circular  opening  in  the  front  end. 

The  chief  distinctive  characters  of  the  Diptera  are: 

Insects  which  when  adult  have,  with  a  few  wingless  exceptions,  only  two 
wings,  these  attached  to  the  mesothorax;  the  hind  wings  greatly  modified, 
each  consisting  of  a  small  knob  attached  to  the  metathorax  by  a  stalk,  these 
structures  being  called  halteres;  mouth  parts  for  sucking,  and  sometimes 
for  piercing  also.  The  larvce  are  called  maggots  and  are  without  true 
legs.  Metamorphosis  complete. 

This  is  one  of  the  large  orders  of  insects  and  members  of  the  group 


304  APPLIED  ENTOMOLOGY 

are  found  in  all  parts  of  the  world.  They  differ  greatly  in  their  habits, 
food,  and  general  modes  of  life.  Some  are  serious  pests  either  of  crops 
or  of  man,  while  others  are  among  the  most  beneficial  insects  known, 
acting  as  parasites.  A  number  of  species  function  as  carriers  of  disease- 
producing  organisms  and  are  of  importance  in  that  way. 

About  fifty  families  of  Diptera  are  recognized,  many  of  them  very 
large  while  others  contain  few  species. 


FIG.  320.- — Large  Crane-fly  (Tipulid),  head  bent  downward  and  almost  wholly  concealed; 
halter  of  right  side  showing  plainly.      Natural  size.      (Original.) 

Family  Tipulidse  (The  Crane-flies). — This  is  a  large  and  widely  distributed 
family  composed  of  Diptera  having  long  and  rather  slender  bodies  and  very  long 
legs;  in  fact  resembling  enormous  mosquitoes  in  appearance  though  a  few  are 
very  small  (Fig.  320).  The  antennae  are  generally  thread-like  and  there  is  a  broad 
V-shaped  groove  or  suture  on  the  top  of  the  thorax. 

The  larvae  of  crane-flies  in  most  cases  live  in  the  ground  and  feed  on  the  roots 
of  grasses  and  grain  and  at  times  cause  much  injury  in  this  way.  Some  exceptions 
live  in  decaying  wood,  on  leaves,  in  water  or  elsewhere.  There  seem  to  be  two 
generations  each  year,  adults  appearing  in  the  spring  and  fall,  and  winter  is 
passed  as  the  partly-grown  maggot.  Injury  is  most  often  noticed  on  low  or  poorly 
drained  land  or  where  a  field  has  been  left  in  grass  for  a  number  of  years.  Control 
of  these  insects,  when  they  are  sufficiently  injurious  to  make  it  pay,  is  by  drain- 
ing,.  rotation  of  crops  and  plowing  early  in  the  fall,  when  the  insects  are  in  the 
pupa  stage  just  below  the  surface  of  the  ground,  to  crush  them  there. 


THE  DIPTERA 


305 


Family  Culicidae  (The  Mosquitoes). — These  are  small  insects,  famil- 
iar to  everyone  as  they  attack  man  and  other  animals,  and  in  most 
species  the  females  feed  upon  blood.  A  few  species  appear  to  consume 
plant  juices.  The  mouth  parts  of  the  males  are  much  reduced  and  the 
members  of  this  sex  rarely,  if  ever,  feed.  There  are  many  kinds  of 
mosquitoes  but  the  larvae  of  all  live  in  water  and  generally  not  in  large 
ponds  but  in  more  or  less  stagnant  water,  and  the  most  abundant  species 
develop  in  temporary  pools. 

The  adults  have  scales  fringing  their  wings  and  also  along  the  veins. 
The  antennae  of  the  males  are  plumose  (feather-like)  and  very  noticeable. 
The  winter  is  passed  either  as  the 
egg,  larva  or  adult,  according  to 
the  species  concerned. 

The  eggs  may  be  laid  either 
singly,  in  small  clusters,  or  in 
masses  often  called  "rafts"  on  the 
surface  of  standing  water  or  even 
on  the  ground,  hatching  in  the 
latter  case  after  rains  or  the  melt- 
ing of  the  snow  in  spring.  The 
number  of  eggs  laid  by  one  insect 
varies  in  different  species  but 
probably  averages  several  hundred. 

The  larvae  or  "wigglers"  live 
in  water  and  move  with  a  motion 
which  has  given  them  their  com- 
mon name.  The  head  and  thorax 
are  large  and  distinct,  while  the 
abdomen  is  slender,  and  projecting 
from  next  to  the  last  segment  of 
this  section  of  the  body  is  a  re- 
spiratory tube  which  is  usually 

rather  long  and  near  the  end  of  which  the  breathing  organs  open  by 
a  sort  of  spiracle.  When  air  is  desired,  the  larva  floats  to  the  surface 
and  projects  the  tip  of  the  respiratory  tube  just  above  the  water  level, 
to  renew  its  supply  (Fig.  321). 

The  larvae  have  mouth  parts  of  the  chewing  type,  and  some  are  plant 
feeders.  Most  of  them,  however,  are  predaceous,  feeding  on  tiny  water 
animals  and  even  on  other  mosquito  larvae,  a  pair  of  small  brushes 
at  the  mouth  being  used  to  cause  currents  in  the  water  and  bring  food 
within  their  reach.  They  molt  four  times  and,  after  a  varying  length 
of  time  (a  week  or  10  days  in  many  cases)  in  different  species  and  at 
different  seasons  of  the  year,  transform  into  pupae.  These  are  quite 
different  in  appearance  from  the  larvae,  the  head  and  thorax  forming  a 
20 


FIG.  321. — Breathing  position  of  larva 
of  Culex  (below),  and  feeding  and  breath- 
ing position  of  Anopheles  (above).  Much 
enlarged.  (Modified  from  U.  S.  D.  A.  Div. 
Ent.  Bull.  25,  n.  s.) 


306  APPLIED  ENTOMOLOGY 

large,  rounded  mass,  joined  by  a  slender  abdomen.  Differing  from 
most  insect  pupae,  the  pupal  mosquito  is  active,  moving  through  the 
water  by  a  curious  tumbling  end  over  end.  On  the  top  of  the  thorax 
in  this  stage  are  two  breathing  tubes  (Fig.  322),  and  when  air  is  desired 
the  tips- of  these  are  pushed  above  the  surface  of  the  water.  The  animal 
swims  by  making  use  of  a  pair  of  leaf -like  appendages  at  the  end  of  the 
abdomen. 

After  a  brief  pupal  stage,  usually  lasting  only  a  few  days,  the  animal 
comes  to  the  surface  of  the  water  and  a  split  of  the  pupal  skin  along  the 
middle  of  the  back  of  the  thorax  appears,  through  which  the  adult 
mosquito  escapes,  balancing  itself  on  this  skin  until  it  is  ready  for  flight. 


FIG.  322. — Pupa  of  Anopheles  (left)  and  of  Culex  (right)  showing  position  when  breath- 
ing. Difference  of  form,  position  in  the  water  and  in  the  breathing  tubes  are  shown. 
Greatly  enlarged.  (Modified  from  U.  S.  D.  A.  Div.  Ent.  Bull.  25,  n.  s.) 


Of  the  many  kinds  of  mosquitoes  known,  a  small  number  are  of 
particular  importance  aside  from  their  habit  of  attacking  man,  being 
disease-carriers. 

The  House  Mosquito  (Culex  pipiens  L.). — This  is  a  very  common 
species  almost  everywhere  in  the  Northern  United  States  east  of  the 
Mississippi  River  and  north  of  North  Carolina.  It  is  probably  a  native 
of  the  Old  World  where  it  is  also  abundant.  Though  as  far  as  known  it 
is  not  a  carrier  of  any  human  disease  yet  it  is  a  most  irritating  pest,  and 
its  control  is  important  on  that  account. 

Winter  is  passed  as  the  adult  (Fig.  323)  in  protected  places  and,  in 
spring,  egg  clusters  containing  from  100  to  about  300  eggs  are  laid  on  the 
surface  of  water.  These  eggs  hatch  in  from  1  to  4  or  5  days  and  the 
larval  stage  usually  continues  for  a  week  or  two  (Fig.  324) .  During  this 
period,  the  larvae  spend  much  of  their  time  at  the  surface,  the  respiratory 
tube  projecting  slightly  above  the  water-line  and  the  body  hanging 
downward.  Pupation  for  a  few  days  follows,  after  which  the  adult 
appears.  There  are  a  number  of  generations  each  season.  The  adult 


THE  DIPTERA 


307 


has  unspotted  wings  and,  when  at  rest,  its  body  is  parallel  to  the  object  on 
which  it  has  alighted  (Fig.  325). 

A  number  of  other  species  not  concerned  in  carrying  disease    are 
also  liable  to  be  pests.     Near  salt  marshes  of  the  eastern  and  southern 


FIG.  323.  FIG.  324. 

FIG.  323. — Male  House  Mosquito  (Culex  pipiens  L.),  greatly  enlarged.  Note  the 
large  feathery  antenna  of  this  sex.  (From  U.  S.  D.  A.  Div.  Ent.  Bull.  25,  u.  s.) 

FIG.  324. — Larva  of  House  Mosquito,  greatly  enlarged.  (After  Howard,  Dyar  and 
Knab.) 


FIG.  325. — Alighting  positions  of  Anopheles  (left)  arid  Culex  (right)  Mosquitoes. 
U.  S.  D.  A.  Div.  Ent.  Bull.  25,  n.  s.) 


(From 


United  States,  the  Salt  Marsh  Mosquito  (Aedes  sollicitans  Walk.)  is 
very  troublesome,  and  this  species  may  fly  quite  a  long  distance  inland. 
In  the  West,  other  species  are  abundant. 

The  Malarial  Mosquitoes  (Anopheles  quadrimaculatus  Say  and 
others). — The  species  of  Anopheles  are  carriers  of  malaria.  The  adults 
(Fig.  326)  are  larger  than  those  of  the  House  Mosquito  and  their  wings 


308 


APPLIED  ENTOMOLOGY 


are  marked  with  dark  spots.  In  alighting  on  an  object,  the  body  is 
tipped  at  quite  an  angle  to  the  object  on  which  it  rests  (Fig.  325)  and 
these  two  differences  will  at  once  serve  to  distinguish  the  malarial  mosqui- 
toes from  other  species.  Another  distinction  is  in  the  length  of  the  palpi 
of  the  female  which  in  the  House  Mosquito  are  short,  while  in  the  Malarial 
Mosquito  they  are  as  long  as  the  beak  and  therefore  quite  noticeable. 
The  species  of  Anopheles  named  above  is  found  from  Canada  to 
Mexico,  east  of  the  Rocky  Mountains. 


FIG.  326.  FIG.  327. 

FIG.  326. — Female  Malarial  Mosquito  (Anopheles  punctipennis  Say)  much  enlarged. 
Antenna  of  male  at  right.  (From  U.  S.  D.  A.  Div.  Ent.  Bull.  25,  n.  s.) 

FIG.  327. — Larva  of  Malarial  Mosq.uito,  greatly  enlarged.  (After  Howard,  Dyar 
and  Knob.} 


Winter  is  passed  as  the  adult,  and  the  eggs  are  laid  singly  on  the 
surface  of  water  and  hatch  2  or  3  days  later.  The  larvae  (Fig.  327) 
resemble  those  of  the  House  Mosquito  but  have  a  shorter  respiratory 
tube  and  lie  horizontally  just  below  the  surface  instead  of  hanging  head 
downward.  (Fig.  321).  The  larval  period  is  about  2  weeks,  followed  by 
a  pupal  stage  lasting  2  or  3  days.  Accordingly,  a  new  generation  of 
these  mosquitoes  may  appear  about  every  3  weeks. 

Most  species  of  Anopheles  attack  man  chiefly  during  the  twilight 
and  early  morning  hours.  The  various  species  of  Culex  seek  their  food 
at  night  though  often  beginning  their  work  late  in  the  afternoon. 


THE  DIPTERA  309 

Different  species  of  Anopheles  appear  to  be  connected  with  different 
types  of  malaria.  Anopheles  quadrimaculatus  has  been  proved  to  carry 
the  organisms  causing  both  the  tertian  and  quartan  forms  while  Anopheles 
crucians  is  a  carrier  of  the  organisms  producing  the  sestivo-autumnal 
type  of  the  disease,  and,  in  other  parts  of  the  world,  other  species  play 
similar  roles  in  relation  to  these  forms. 

The  animals  causing  malaria  are  believed  to  be  of  three  closely 
related  kinds,  belonging  to  the  Protozoa.  In  its  form  when  introduced 
into  the  blood  of  man,  the  animal  is  a  rather  long  and  slender  spindle 
with  pointed  ends.  It  now  assumes  an  amoeboid  form  and  attacks  a 
red  blood  corpuscle,  working  into  it,  feeding  on  its  haemoglobin  contents 
and  producing  black  granules.  It  feeds  on  the  haemoglobin  in  the 
corpuscle  until  this  has  all  been  consumed  and  grows  until  it  nearly  fills 
the  corpuscle.  It  now  divides  into  many  parts,  each  similar  to  the  one 
which  first  entered  the  corpuscle,  and  these  proceed  to  attack  other 
corpuscles  in  a  similar  way.  This  breaking  up  of  the  animal  into  parts 
coincides  with  the  " chill"  of  the  disease  and  the  interval  of  time  between 
successive  chills  determines  which  type  of  malaria  is  present,  a  period  of 
2  days  indicating  the  tertian  type;  3  days  the  quartan  type,  while  a 
varying  period  indicates  the  sestivo-autumnal  type.  As  the  parasites 
increase  in  abundance  and  consume  more  of  the  corpuscles,  the  patient 
becomes  anaemic  and  weaker. 

Some  of  the  products  of  division  in  the  corpuscle,  however,  do  not 
proceed  to  attack  other  corpuscles  and  increase  in  numbers  but  are  of 
two  different  kinds  which  are  the  sexual  stages.  When  these  are  taken 
into  the  stomach  of  an  Anopheles  which  attacks  a  person  having  malaria, 
the  two  kinds  fuse  and  the  resulting  animal  penetrates  the  cells  of  the 
stomach  wall  of  the  mosquito  and  there  remains,  forming  a  cyst.  Divi- 
sion of  the  animal  here  results  finally  in  the  production  of  cells  like  those 
which  enter  human  blood,  and  these  now  escape  into  the  body  cavity  of 
the  mosquito  and  gradually  gather  in  its  salivary  glands  whence,  they 
are  expelled  into  the  wounds  caused  by  the  feeding  of  the  mosquito  there- 
after. The  time  which  must  elapse  after  a  mosquito  has  received  the 
malarial  parasites  before  it  can  transmit  these  to  man  varies,  but  is 
usually  at  least  10  or  12  days  and  may  in  some  cases  be  more  than  this. 

The  Yellow  Fever  Mosquito  (Aedes  .cegypti  L.). — This  insect,  for- 
merly known  as  Stegomyia  fasciata,  is  the  carrier  of  Yellow  Fever.  It 
occurs  in  the  tropics  throughout  both  hemispheres  and,  during  warm 
weather,  may  extend  to  the  temperate  regions  but  can  survive  there 
only  while  the  temperature  is  fairly  high. 

The  adult  (Fig.  328)  is  a  small  mosquito  with  silvery  lines  along  the 
back  of  the  thorax  and  its  legs  are  banded  with  white.  It  flies  in  the 
daytime  and  occurs  mainly  in  towns  and  cities,  being  only  rarely  found 
in  the  country.  Its  eggs  are  laid  singly  or  in  small  clusters  on,  or  close 


310 


APPLIED  ENTOMOLOGY 


to,  water  in  houses  or  near  by,  it  having  apparently  become  a  "  wholly 
domesticated"  species.  The  eggs  hatch  in  from  10  hr.  to  about  3  days, 
and  the  larvae  hang  downward  from  the  surface.  After  a  week  or  10 
days  in  this  stage,  they  pupate  for  2  or  3  days  before  the  emergence  of  the 
adult.  Feeding  by  the  adult  appears  to  be  mainly  during  the  warmer 
hours  of  sunny  days  though  extending  somewhat  into  the  evening. 

Repeated  investigations  show  that  the  unknown  germ  or  organism 
producing  Yellow  Fever  is  conveyed  to  man  only  by  the  attacks  of  this 
insect.  Apparently  about  12  days  is  required  after  feeding  on  a  Yellow 
Fever  patient  before  the  mosquito  is  able  to  transmit  the  organism  caus- 
ing the  disease,  but  from  that  time  on  it  can  do 
this  for  well  over  a  month. 

Dengue  and  Filariasis,  two  other  important 
diseases  of  man  in  tropical  and  subtropical 
regions,  are  also  known  to  be  carried  by 
mosquitoes. 

Control  of  Mosquitoes. — There  are  many 
ways  by  which  mosquitoes  can  be  more  or  less 
effectively  controlled.  The  thorough  screening 
of  houses  to  keep  them  out  is  a  desirable  prac- 
tice and  is  also  of  value  as  a  protection  against 
house-flies.  Nettings  over  beds  for  the  same 
purpose  are  often  used  where  entire  houses  are 
unscreened.  Out-of-doors,  veils  covering  the 
head,  and  gloves  for  the  hands  are  often  necessary 
in  places  where  these  insects  are  extremely 
abundant.  Protective  materials  rubbed  on  ex- 
posed parts  of  the  body  are  also  often  used  and 
various  substances  have  proved  of  value  for  this  purpose.  Among  these 
are  spirits  of  camphor,  oil  of  pennyroyal  and  oil  of  citronella  which  seem 
to  be  the  favorite  substances  used  in  this  way.  Smudges  will  keep  away 
mosquitoes  where  the  smoke  is,  and  burning  insect  powder  in  a  room 
stupifies  the  insects  so  that  they  fall  to  the  floor  and  can  be  swept  up. 
Other  materials  for  use  in  a  similar  way  are  also  available. 

Destruction  of  the  larvae,  pupae  and  eggs  is  the  most  direct  way  in 
which  to  control  mosquitoes  in  large  numbers,  and  many  methods  for 
accomplishing  this  have  been  tried.  As  mosquitoes  develop  only  in 
water,  the  removal  of  the  places  where  they  can  breed,  such  as  the  drain- 
age of  marsh  land,  filling  up  small  pools,  hollows  in  trees  containing 
standing  water,  and  all  such  situations  will  accomplish  a  great  deal. 
The  drainage  of  the  salt  marshes  of  the  New  Jersey  coast  and  elsewhere 
has  resulted  in  a  marked  relief  from  the  attacks  of  mosquitoes  in  those 
localities.  Where  the  water  can  not  be  drained  off,  covering  it  with  a 
film  of  kerosene  will  suffice  to  destroy  the  eggs  on  the  surface,  larvae  and 


FIG.  328.— Adult  Yellow 
Fever  M  o  s  q  u  i  t  o  ( A  cdes 
ccyypti  L.),  considerably  en- 
larged. Note  black  and 
white  banding  of  the  legs. 
(After  U.  S.  D.  A.  Farm. 
Bull.  547.) 


THE  DIPT  ERA  311 

pupae  at  or  coming  to  the  surface  for  air,  and  any  adults  which  may  alight 
on  the  water  to  lay  their  eggs.  Rain  water  barrels  and  cisterns  for  storing 
water  for  use  can  be  screened,  and  ponds  where  the  use  of  oil  is  undesirable 
may  be  stocked  with  small  fish  (sun-fish  or  top  minnows)  which  feed 
voraciously  on  these  insects.  Recent  experiments  indicate  that  where 
the  water  must  be  used  for  drinking  purposes,  making  the  use  of  oil 
objectionable,  sprinkling  powdered  formalin  on  its  surface  will  kill 
mosquito  larvae  but  not  fish  present,  without  making  the  water  impossible 
to  drink! 

The  catch-basins  of  sewer  openings  are  usually  favorite  breeding  places 
for  mosquitoes  and  these  must  be  given  attention,  along  with  cess-pools 
and  any  tin  cans  or  other  receptacles  containing  rain  water  which  can  be 
found. 

Oil  used  should  be  sprayed  on  the  water,  working  preferably  along  its 
windward  side  and  using  about  1  fl.  oz.  to  every  15  sq.  ft.  of  surface. 
The  oil  will  spread  if  simply  poured  onto  the  water,  but  rather  more  of  it- 
will  be  required  by  that  method.  It  is  important  to  be  sure  that  little 
detached  pools  along  the  shore  receive  their  film  of  oil  also.  This  treat- 
ment should  be  repeated  every  10  to  15  days  unless  heavy  rains  carry  off 
the  oil  soon  after  a  treatment,  in  which  case  the  oil  should  be  renewed 
sooner.  Sawdust  soaked  in  kerosene  has  been  found  to  give  up  the  oil 
slowly  and  thereby  preserve  the  film  on  the  surface  longer,  when  this 
material  is  scattered  along  the  edge  of  the  water. 

Family  Itonididae  (The  Gall  Midges). — These  tiny  flies  are  very 
numerous.  Most  of  them  produce  galls  on  plants,  living  in  these  galls, 
but  some  suck  plant  juices  without  producing  galls,  and  a  few  live  in 
decaying  wood  or  fungi,  or  even  feed  on  Aphids.  The  adults  have  long 
antennae  with,  in  the  majority  of  the  species,  a  whorl  of  hairs  on  each 
segment.  All  parts  of  the  plant  are  attacked  by  one  species  or  another, 
and  the  galls  produced  are  typical  for  the  species  in  each  case. 

The  gall  appears  to  be  the  result  of  the  irritation  caused  by  the  larva 
feeding,  and  to  some  extent  its  size  is  dependent  upon  the  number  of 
larvae  present.  Winter  is  frequently  spent  as  the  larva  inside  the  gall 
and,  in  many  cases,  there  is  but  one  generation  each  year  though,  on  the 
other  hand,  some  species  have  several  generations. 

The  larvae  are  small,  often  brightly  colored  maggots.  The  method  of 
pupation  varies  in  different  species,  some  forming  true  cocoons  while 
others  have  a  puparium  and  others  are  without  any  covering. 

Among  the  species  not  producing  galls  is  the  Clover-flower  Midge  (Dasyneura 
leguminicola  Lint.)  which  lays  its  eggs  in  the  flower  heads  of  mammoth,  red, 
crimson  and  white  clover  and  is  probably  present  everywhere  in  America  where 
these  clovers  occur.  There  are  two  generations  each  year.  The  larvae  feed  on 
the  flowers  and  prevent  their  forming  seed.  As  the  insects  do  not  affect  other 
parts  of  the  plant,  they  are  fcot  of  serious  importance  except  where  seed  is  grown, 


312 


APPLIED  ENTOMOLOGY 


but  in  those  localities  they  are  very  injurious  pests.  The  usual  methods  of  control 
are  to  pasture  the  fields  before  starting  a  seed  crop,  to  destroy  all  the  midges 
present  in  the  heads  then  available:  by  early  cutting,  to  dry  up  the  heads  before 
the  maggots  in  them  have  finished  feeding,  which  in  the  northern  districts  would 
mean  cutting  early  in  June.  Sometimes,  cutting  the  clover  back  between  the 
fifteenth  and  twenty-fifth  of  May  will  prove  advantageous  as  the  new  blossoms 
will  not  develop  until  after  the  adults  of  the  first  generation  are  gone,  and  will 
have  progressed  beyond  danger  of  injury  by  the  time  the  adults  of  the  second 
generation  appear.  Clover  so  cut  can  be  fed  green  to  stock. 

The  Hessian  Fly  (Phytophaga  destructor  Say). — This  insect,  which 
like  the  last  is  one  of  the  non-gall-making  Itonididse,  is  a  native  of  Europe 
and  was  first  noticed  in  this  country  about  1779  on  Long  Island,  N.  Y. 
Since  that  time,  it  has  spread  over  a  large  part  of  the  United  States  and 

Canada  and  is  now  one  of  the  most 
injurious  insect  pests  in  the  country, 
often  destroying  wheat  valued  at 
millions  of  dollars.  It  feeds  on  wheat, 
barley,  rye,  and  several  other  species 
of  grasses. 

Its  life  history  differs  somewhat  in 
different  places,  apparently  being 
modified  by  the  different  methods  of 
wheat  growing.  Where  wheat  is 
planted  in  the  fall,  the  eggs  are  laid 
on  the  leaves  of  the  plants  soon  after 
they  come  up,  the  time  varying  with 
the  latitude  from  late  August  and 
September  in  Michigan,  to  the  last  of 
November  or  early  December  in 
Georgia.  The  eggs  are  placed  in  ir- 
regular rows  of  about  half  a  dozen, 

generally  on  the  upper  surface  of  the  leaf,  and  each  fly  lays  100  to  150  in 
all.  They  hatch  after  a  few  days,  and  the  tiny  pinkish  or  reddish  maggots 
work  their  way  down  between  the  leaf  and  the  stem  to  a  point  just  above 
the  joint  (Fig.  329).  Here  they  remain,  sucking  the  sap  until  the 
approach  of  cold  weather,  turning  more  nearly  white  in  color.  Their 
presence  at  this  time  is  at  first  indicated  by  the  dark  color  of  the  leaves, 
missing  stems  which  would  otherwise  begin  to  show,  and  later,  the  yellow- 
ing and  death  of  the  plants.  After  feeding  about  a  month,  the  larva 
pupates  within  its  larval  skin  which  therefore  becomes  a  puparium  and  so 
greatly  resembles  a  flax-seed  that  in  this  condition  the  insect  is  generally 
spoken  of  as  being  in  the  " flax-seed"  stage.  In  this  condition,  it  spends 
the  winter  and  the  adult  flies  (Fig.  329)  emerge  in  the  spring;  early  in  the 
South;  later  in  the  North.  These  now  lay  their  eggs  on  the  wheat  and, 


FIG.  329.— Hessian  Fly  (Phytophaga 
destructor  Say):  a,  adult  fly;  b,  wheat 
plant  affected;  c,  maggot.  Hair  lines 
show  true  length  of  a  and  c.  (From 
Berlese.) 


THE  DIPTERA  313 

as  by  this  time  the  plants  may  be  a  number  of  inches  high,  the  eggs 
can  be  laid  at  different  heights  on  the  plant,  and  the  larvae  will  pass  down 
to  the  joints  immediately  below  the  leaves  on  which  the  different  eggs 
are  laid.  Feeding  at  these  joints  continues  during  the  spring  and  the 
flax-seed  stage  is  reached  at  or  before  harvesting  time.  Some  of  the 
flax-seeds  will  be  in  the  straw  cut  and  harvested  while  many  more  will 
remain  in  the  stubble  and  the  flies  emerge  from  the  flax-seeds  during  the 
early  fall  as  already  indicated,  ready  to  attack  the  fall-planted  wheat  as 
soon  as  it  comes  up. 

In  regions  where  the  wheat  is  planted  in  the  spring,  the  insect  winters 
in  the  flax-seed  stage  in  stubble  and  volunteer  wheat,  and  the  adults 
appear  in  May.  The  second  generation  quickly  follows  the  first,  particu- 
larly in  wet  seasons,  and  there  seems  to  be  no  period  of  delay  such  as 
occurs  during  midsummer  in  the  fall-wheat  regions. 

Control. — The  Hessian  Fly  has  numerous  parasites  which  are  undoubt- 
edly of  much  value,  as  where  great  loss  occurs  these  insects  are  few  in 
number.  It  is  so  often  the  case,  though,  that  the  fly  is  abundant,  that 
parasites  can  not  be  relied  upon  and  other  measures,  largely  preventive 
in  their  nature,  must  be  taken. 

It  is  evident  that,  if  fall  planting  can  be  delayed  until  the  adults 
which  appear  at  that  time  are  gone,  the  crop  will  be  protected  from 
attack.  To  carry  out  this  plan,  however,  latitude,  elevation  and  humid- 
ity perhaps,  as  well,  must  be  taken  into  consideration.  Investigations 
along  this  line,  though  far  from  complete,  now  indicate  that  it  is  generally 
safe  to  plant  wheat  in  northern  Michigan  after  the  first  of  September: 
in  southern  Michigan  and  northern  Ohio,  about  the  twentieth  of  that 
month:  in  southern  Ohio,  after  October  7:  in  Kentucky,  after  October 
15 :  and  in  Georgia,  from  the  last  week  in  October  to  the  middle  of  Novem- 
ber. Thus  in  general,  the  farther  south,  the  later  the  planting  date 
should  be,  though  very  high  land  in  any  region  can  probably  be  planted 
earlier  than  low  land  if  the  area  and  elevation  are  sufficient  to  give  it  the 
more  northern  conditions. 

The  rotation  of  crops  is  also  of  advantage,  driving  the  flies  elsewhere 
to  lay  their  eggs  and  making  them  more  liable  to  destruction  while 
en  route. 

Many  of  the  flax-seeds  are  left  in  the  stubble  at  harvesting  and 
any  method  of  destroying  these  is  beneficial.  Where  the  grain  is  cut 
rather  high  and  a  mowing  machine  is  then  run  over  the  field,  cutting 
the  stubble  as  close  as  possible,  burning  this  cut  stubble  after  a  few  days' 
drying  is  effective.  Unfortunately,  however,  the  general  custom  of 
planting  grass  and  clover  in  such  fields,  to  come  up  as  the  grain  progresses 
toward  harvesting,  too  often  makes  this  control  impracticable. 

Volunteer  wheat  as  it  is  called,  coming  from  grain  scattered  through 
and  around  the  wheat  fields  by  accident,  starts  early  and  provides  plants 


314  APPLIED  ENTOMOLOGY 

for  the  Hessian  Fly  to  lay  its  eggs  on  before  the  main  planting  is  avail- 
able. This  will  produce  an  abundance  of  the  insects  to  attack  the  crop 
the  following  spring.  All  such  plants  should  be  destroyed  before  the 
maggots  in  them  have  reached  the  flax-seed  stage. 

The  use  of  good  seed,  planted  in  soil  that  has  been  thoroughly  culti- 
vated to  break  up  all  the  lumps  of  dirt  and  thus  provide  a  compact, 
fine  soil,  is  very  helpful,  and  the  addition  of  plenty  of  fertilizer  is  also  of 
importance. 

One  writer  has  summarized  control  methods  for  the  Hessian  Fly 
as  follows:  "Sow  the  best  of  seed  in  thoroughly  prepared,  fertile  soil 
after  the  major  portion  of  the  fall  brood  has  .  .  .  passed  out  of  existence, 
and,  if  possible,  sow  on  ground  not  devoted  to  wheat  the  preceding  year. 
In  the  spring-wheat  section  late  seeding  will  not  apply.  It  seems  likely, 
on  the  contrary,  that  the  earlier  it  is  sown  in  spring  the  less  it  will  suffer 
from  the  Hessian  Fly,  "  (Webster). 

Another  Itonidid  attacking  wheat,  and  also  barley,  rye  and  oats  occasionally 
is  the  Wheat  Midge  (Contarinia  tritici  Kirby),  a  native  of  Europe,  first  noticed 
near  Quebec  about  1819,  and  which  has  now  spread  over  the  wheat-growing 
regions  of  the  East,  and  through  the  Mississippi  Valley.  The  adults  are  very 
small,  yellow  or  orange  colored,  and  appear  in  June.  They  lay  their  eggs  in  the 
chaff  covering  the  growing  kernels  of  grain,  and  the  reddish  maggots  suck  the 
juice  from  the  kernels  causing  them  to  shrivel,  blighting  the  heads.  When  full- 
grown,  the  maggots  pupate  in  the  ground,  usually  passing  the  winter  in  this  stage. 
There  is  generally  only  one  generation  each  year. 

For  many  years,  this  was  a  very  serious  enemy  of  wheat,  the  loss  in  New  York 
being  estimated  at  $15,000,000  in  1854,  but  since  about  1860  it  has  been  less 
destructive  and  only  local  in  its  attacks.  Plowing  infested  land  deeply  in  the  fall 
so  that  the  insects  wintering  there  will  be  buried  too  deeply  for  them  to  escape 
the  following  spring:  burning  the  chaff  and  screenings  after  threshing  the  grain 
from  infested  fields,  and  rotation  of  crops  are  the  control  methods  used  for 
this  pest. 

Family  Tabanidae  (The  Horse  Flies  or  Gad  Flies). — These  pests  of 
cattle,  horses,  and  occasionally  of  man  also  (Figs.  330  and  331)  are  in  many 
cases  quite  large  insects,  with  bodies  an  inch  long  though  most  of  them 
average  a  third  to  half  an  inch  in  length.  The  head  of  the  adult  is  large 
and  fits  onto  the  thorax  somewhat  like  a  cap.  Only  the  females  feed 
on  blood,  the  males  lacking  some  of  the  mouth  parts  necessary  with 
which  to  pierce  the  skin.  They  therefore  feed  on  such  plant  juices  as 
they  may  be  able  to  obtain,  honey  dew  and  other  similar  materials. 

The  eggs  are  laid  in  masses  on  plants  over  water  or  marshes,  and  the 
larvae  live  in  water,  damp  places,  or  in  the  earth  when  it  is  soft,  and  are 
carnivorous,  feeding  on  snails,  small  insect  larvae,  etc. 

The  family  is  a  large  one,  both  in  this  country  and  elsewhere.  The 
larger  species,  (one  has  a  black  body  and  smoky  wings) ,  are  often  noticed 


THE  DIPTERA 


315 


around  domestic  animals  because  of  their  size.  Many  of  the  smaller  kinds 
have  wings  banded  with  dark.  Some  of  these  are  called" Green-heads" 
because  of  the  bright  green  color  of  their  eyes  (Fig.  331).  Their  attacks 
irritate  and  disturb  the  animals  and,  in  the  case  of  milch  cattle,  this 
may  reduce  the  amount  of  milk  produced. 

As  these  insects  attack  domestic  animals  only  for  their  blood,  any 
repellent  measures  which  prevent  this  are  sufficient.  Fly-nets  covering 
the  greater  part  of  the  animals  are  sometimes  used  for  this  purpose:  and 
smearing  the  ears  and  legs  with  substances  having  an  odor  objectionable 
to  the  flies  is  also  practiced.  One  of  several  materials  often  applied  is 
fish  oil,  either  alone  or  mixed  with  tar.  The  following  mixture  has  proved 


FIG.  330.  FIG.  331. 

FIG.  330. — Large  Horse  Fly  (Tabanus  stygius  Say),  slightly  reduced.     (Original.) 
FIG.  331. — Small   Horse   Fly    (Chrysops  mttatus    Wied.),     over    twice    natural    size. 
(Original.) 

effective  against  those  Tabanids  which  preferably  attack  the  ears  and  the 
region  around  the  eyes  of  the  animals:  pine  tar,  1  gal.;  fish  oil  or  crude 
carbolic  acid,  1  qt.;  powdered  sulfur,  2  Ib.  These  materials  are  thor- 
oughly mixed  and  rubbed  on  the  parts  most  liable  to  be  attacked.  As  so 
many  Tabanids  pass  their  early  stages  in  stagnant  water,  the  treatment 
of  such  breeding  places  with  kerosene  will  destroy  the  larvae  as  they  hatch 
and  enter  the  pools. 

Family  Simulidae  (The  Black  Flies  or  Buffalo  Gnats). — The  small  flies  which 
compose  this  family  feed  upon  the  blood  of  man  and  other  animals,  attacking 
them  at  all  exposed  places.  As  in  the  Tabanidse,  only  the  females  are  concerned 
and  these  are  active  only  during  the  daytime.  The  eggs  are  laid  in  such  places 
that  the  larvae  can  enter  water,  and  in  most  cases,  swiftly  running  streams  where 
they  feed  on  small  animals.  They  usually  anchor  themselves  to  some  object  in 
the  water  and  have  a  pair  of  fan-shaped  structures  at  the  mouth  which  are  used 
to  produce  currents  toward  the  mouth.  In  the  South,  all  domestic  animals  suffer 
severely  from  the  attacks  of  these  insects,  and  many  are  even  killed  by  them. 
There  are  usually  two  or  three  generations  each  year,  particularly  in  the  South. 
The  best  control  methods  known  are  the  use  of  repellent  materials  on  the  animals, 
such  as  fish  oil  three  parts,  kerosene  one  part,  applied  about  twice  a  day.  Ani- 
mals kept  in  dark  stables  are  not  attacked  while  there. 


316 


APPLIED  ENTOMOLOGY 


Family  Asilidae  (The  Robber  Flies). — These  insects  as  adults  prey 
upon  other  insects,  attacking  any  species  they  are  able  to  overcome  (Fig. 
332),  but  using  little  discrimination  as  to  the  importance  to  man  of  their 
captures.  They  can  hardly  be  regarded  as  more  than  accidentally 
beneficial  to  man.  Some  species  (Fig.  333)  so  closely  resemble  bumble- 
bees that  a  careful  examination  of  the  number  of  wings  present  is  necessary 
to  determine  what  the  insect  is.  The  larvae  are  found  chiefly  under  bark, 
in  decaying  wood  or  in  the  ground  where  decaying  vegetable  matter  occurs, 
and  feed  upon  insect  larvae  present  in  such  places. 


FIG.  332. 

FIG.  332.  —  Robber    Fly    (Scleropogon    picticornis    Loew), 
(From  U.  S.  D.  A.  Bull.  124.) 

FIG.  333.—  Bee-like  Robber  Fly  (Dasyllis  grossa  Fab.),  slightly  reduced.      (Original.) 


FIG.  333. 
about    twice    natural    size. 


This  family  is  one  of  the  largest  in  the  order  and  its  members  average 
large,  ranging  from  a  length  of  about  a  fifth  of  an  inch  to  nearly  two  inches. 

Family  Syrphidae  (The  Syrphus  Flies).  —  This  is  one  of  the  largest 
families  of  Diptera.  The  adults  range  from  quite  small  to  rather  large 
insects  which  visit  flowers,  feeding  on  the  pollen  and  nectar,  and  are  most 
noticeably  abundant  in  bright,  sunny  weather.  They  are  usually  rather 
brightly  colored. 

The  larvae  of  these  insects  vary  greatly  in  their  appearance,  five  types 
of  them  having  been  recognized.  Some  are  rather  flattened,  elongate, 
often  green  with  white  spots,  and  are  found  with  clusters  of  plant  lice  on 
which  they  feed.  Others  have  nearly  cylindrical  bodies  and  bore  into 
the  bulbs  of  various  plants.  Others  live  and  feed  in  filth  and  have  short 
extensible  tubes  for  respiration.  Another  class  which  also  inhabits  filth 
has  extensible  respiratory  tubes  which,  when  extended  to  their  limit,  may 
be  several  times  the  length  of  the  body.  Still  another  group  are  short, 
broadly  rounded,  flattened  beneath  and  high  above,  somewhat  hemispher- 


THE  DIPTERA 


317 


FIG.  334. — Adult  female   Bot  Fly   (Gastrophilus  nasalis  L.),   nearly  twice  natural  size. 

(From  U.  S.  D.  A.  Bull.  597.) 


FIG.  335.— Nearly  full-grown  larvse  (bots)  of  a  Horse  Bot  Fly  attached  to  the  inside  wall 
of  the  stomach.     (From  U.  S.  D.  A.  Bull.  597.) 


318 


APPLIED  ENTOMOLOGY 


ical  in  form.  These  are  usually  found  under  logs  and  in  ants'  nests  and 
may  easily  be  mistaken  for  rather  peculiar  snails. 

Though  the  adults  consume  pollen,  their  visits  to  flowers  are  valuable 
to  man  for  the  cross-pollination  and  the  resulting  " setting"  of  seed. 
The  insect-eating  larvae  often  destroy  enormous  numbers  of  insect 
pests,  and  the  filth-inhabiting  forms  are  at  least  cleaning  up  decay- 
ing matter,  which  is  generally  considered  desirable.  On  the  other  hand, 
some  are  injurious  by  boring  into  the  bulbs  of  cultivated  plants,  and  sev- 
eral species  cause  myiasis  in  man  and  some  of  the  domestic  animals,  these 
insects  in  one  way  or  another  entering  the  body  and  passing  through  their 
larval  development  there. 

Family  (Estridae  (The  Bot  Flies). — The  bot  flies  in  their  early  stages 
are  parasites  on  mammals.  The  adults  are  of  medium  to  large  size, 
with  rather  stout,  thick-set  bodies  and  frequently  with  reduced  mouth- 
parts,  not  feeding  in  this  stage  (Fig.  334).  Though  the  group  is  not  a 
large  one,  its  members  are  included  among  the  more  important  pests  of 
domestic  as  well  as  of  other  animals.  The  parasitic  part  of  the  life  of 
these  insects  is  in  some  species  spent  in  the  stomach  (Fig.  335)  or  intes- 
tines, in  others  in  the  pharynx  or  nasal  cavities  and  frontal  sinus,  while 
others  live  under  the  skin. 


FIG.  336.  FIG.  337. 

FIG.  336. — Ox  Warble  Fly  (Hypoderma  Uncata  Vill.).  Real  length  shown  by  hair 
line.  (From  U.  S.  D.  A.  Div.  Ent.  Circ.  25.) 

FIG.  337. — Full-grown  Warble  (larva),  dorsal  view  (left)  and  side  view  (right). 
Real  length  shown  by  hair  line.  (From  U.  S.  D.  A.  Div.  Ent.  Circ.  25.) 

The  Ox  Warbles  (Hypoderma  lineatum  Vill.  and  Hypoderma  bovis  De 
G.). — These  two  insects,  both  natives  of  Europe,  are  present  in  this 
ocuntry,  the  former  widely  distributed,  the  latter  most  abundant  in 
Canada  and  a  few  of  the  Northern  States.  The  adult  fly  (Fig.  336)  is 
about  half  an  inch  long.  The  eggs  of  both  species  are  laid  on  the  hairs  of 


THE  DIPT  ERA  319 

cattle  on  almost  any  part  of  the  body  during  the  late  spring  or  summer 
months,  and  the  larvae  bore  through  the  skin  into  the  connective  tissue 
and  then  wander  through  the  body  in  the  connective  tissues  until  late  fall 
or  winter  when  they  locate  along  the  back,  a  few  inches  from  the  back- 
bone. Here  each  makes  a  hole  through  the  skin  through  which  to  escape 
but  remains  inside,  feeding  on  the  pus  and  bloody  matter  produced  by  its 
presence  there,  and  the  swelling  caused  by  the  insect  is  called  a  "  warble." 
Finally  the  maggot,  now  nearly  an  inch  long  (Fig.  337)  and  grayish-white 
in  color,  works  its  way  out  through  the  hole  and  drops  to  the  ground  which 
it  enters  for  an  inch  or  two,  and  forms  a  pupa  within  a  brown  puparium 
from  which  the  adult  fly  appears  from  3  to  6  weeks  later,  the  larval  period 
within  the  cattle  being  9  or  10  months. 

The  presence  of  the  maggots  of  the  ox  warbles  in  the  cattle  is  shown 
by  a  loss  of  flesh,  reduction  of  the  milk  in  the  case  of  milch  cattle,  and  by 
the  presence,  during  late  fall  and  winter,  of  the  sores  on  the  back. 

Control. — The  chief  control  method  in  general  use  is  squeezing  out  the 
larvae  in  the  back  whenever  they  are  observed  there.  With  a  little 
practice,  pressing  with  the  thumbs  on  the  skin  at  the  sides  of  the  opening 
will  result  in  the  expulsion  of  the  maggots.  During  the  egg-laying  season, 
cattle  in  the  field  may  be  protected  to  a  considerable  extent  by  the  appli- 
cation of  repellents  such  as  are  used  to  keep  off  Tabanids. 

Various  other  bot  flies  attack  different  animals.  Among  them  are 
the  Horse  Bot  Flies  (Gastrophilus  of  several  species),  the  larvae  of  which 
live  in  the  stomach  of  the  horse  during  the  fall,  winter  and  spring  and  the 
Sheep  Bot  Fly  (CEstrus  ovis  L.)  which  in  the  larval  stage  inhabits  the 
nasal  cavities  and  frontal  sinuses  of  sheep  during  the  same  period. 

Family  Trypetidse  (The  Fruit  Flies). — Some  of  these  small  flies  attack 
various  fruits  in  which  their  maggots  tunnel,  ruining  the  fruits.  Others 
mine  the  leaves  of  plants,  occur  in  blossoms  or  form  galls  in  the  stems  or 
roots  of  plants.  Those  which  live  in  fruit  are  of  economic  importance. 
Most  of  the  flies  belonging  here  have  dark  bands,  or  dark  markings 
enclosing  transparent  spots  on  their  wings.  Two  species  attack  cherries; 
one  feeds  in  currants  and  gooseberries;  one  in  the  apple,  thorn,  blueberry 
and  huckleberry,  and  other  species  injure  citrus  fruits. 

The  Apple  Maggot  or  Railroad  Worm  (Rhagoletis  pomonella  Walsh). — This 
insect  is  apparently  a  native  of  this  country  and  its  original  food  seems  to  have 
been  the  berries  of  the  thorn  and  possibly  the  blueberry.  It  has  been  found  in 
various  parts  of  Canada  and  the  eastern  United  States  as  far  south  as  North 
Carolina  and  west  to  Minnesota,  South  Dakota  and  Colorado,  but  is  most  serious 
in  the  northern  and  eastern  portion  of  this  territory. 

The  adult  (Fig.  338)  is  about  a  fifth  of  an  inch  long  and  has  a  wing  spread  of 
about  half  an  inch.  Its  body  is  black  with  light  marks  on  the  upper  side  of  the 
abdomen,  and  the  wings  have  heavy  dark  bands.  The  flies  first  appear  in  the 
orchards  early  in  July  in  New  England  (somewhat  earlier  farther  south)  and 


320 


APPLIED  ENTOMOLOGY 


attack  the  early  varieties  of  apples.  Later  appearing  flies  may  sometimes  be 
found  until  into  September,  and  these  select  fall  and  winter  fruit  for  egg  laying. 
Some  varieties  of  apples  are  much  more  subject  to  the  attacks  of  this  insect 
than  are  others. 

Egg  laying  begins  about  20  days  after  the  fly  emerges  and  probably  continues 
for  2  or  3  weeks,  the  total  number  of  eggs  laid  being  several  hundred.  These 
are  inserted  singly  under  the  skin  of  the  apple  and  preferably  where  the  surface 
is  not  exposed  to  sunlight.  They  hatch  in  4  or  5  days  and  the  little  whitish 
maggots  tunnel  through  the  pulp  of  the  fruit  in  all  directions.  At  first,  the 
rapid  growth  of  the  fruit  may  fill  up  these  tunnels,  but  after  a  time  the  walls 
around  the  tunnels  instead  of  filling  in,  turn  brown  and  the  fruit  softens,  decay 
may  follow,  and  the  entire  apple  is  spoiled  for  sale.  The  maggot  (Fig.  339)  has 
no  real  jaws  with  which  to  tunnel  but  has  a  pair  of  small  hooks  at  the  mouth 
opening  with  which  the  pulp  is  rasped  and  torn,  freeing  the  juice  upon  which 
the  insect  feeds. 


/ 


FIG.  338.  FIG.  339. 

FIG.  338. — Adult  Fly  of  the  Apple  Maggot  (Rhagoletis  pomonella  Walsh),  slightly 
over  three  times  natural  size.  (Reduced  from  Nova  Scotia  Dcpt.  Ayr.  Bull.  9.) 

FIG.  339. — Puparium  (left)  arid  full-grown  maggot  (right)  of  the  Apple  Maggot. 
About  three  times  natural  size.  (Modified  from  Nova  Scotia  Dept.  Agr.  Bull.  9.) 


The  length  of  the  larval  stage  depends  upon  the  temperature  and  upon  the 
ripeness  of  the  fruit.  In  warm  weather  and  with  rather  soft  pulp,  about  2  to  4 
weeks  is  usually  the  time  necessary,  but  with  colder  weather  and  in  late-maturing 
varieties,  growth  toward  maturity  is  delayed  and  some  maggots  may  possibly 
even  winter  in  this  stage  in  extreme  cases.  When  the  larva  has  completed  its 
feeding,  however,  it  leaves  the  fruit  (usually  as  this  becomes  ripe)  and  enters  the 
ground  where  it  burrows  below  the  surface  often  some  distance,  and  pupates  in 
a  puparium  (Fig.  339)  remaining  here  until  the  following  summer  when  the  flies 
emerge.  Where  infested  fruit  is  gathered  and  stored  before  the  maggots  leave  it, 
the  puparia  may  be  found  on  the  bottom  of  the  barrels  or  bins  where  the  fruit  is 
kept.  A  few  of  the  earlier  pupating  maggots  appear  to  transform  to  flies  the 
same  season,  giving  a  second  generation,  but  so  few  do  this  that  it  is  of  little  or  no 
economic  importance.  On  the  other  hand,  a  few  seem  to  require  2  years  for 
the  completion  of  their  life  history. 

The  amount  of  injury  caused  where  this  insect  is  abundant  is  often  very  great, 
particularly  with  early  apples,  a  large  percentage  of  which  may  prove  entirely 
worthless.  Among  the  varieties  which  suffer  severely  are  the  Early  Harvest, 
Gravenstein,  Porter,  Red  Astrachan,  and  Wealthy,  sweet  and  sub-acid  summer 


THE  DIPT  ERA  321 

and  fall  varieties  being  in  general  the  greatest  sufferers  though  winter  varieties, 
as  the  Northern  Spy  and  others,  often  do  not  escape. 

The  adult  flies  feed  freely  and  also  seem  to  require  water  during  their  life, 
specimens  supplied  with  food  but  no  water  dying  within  a  few  days.  They  do 
not  appear  to  fly  freely  for  long  distances  at  least,  and  orchards  in  which  they  are 
abundant  and  others  where  they  are  rather  few  in  number  may  occur  not  very 
far  from  each  other. 

Control. — Infested  fruit  falls  to  the  ground  early,  and  the  maggots  in  it  rarely 
leave  it  for  the  ground  to  pupate  until  about  a  week  later.  Gathering  and 
destroying  this  fallen  fruit  promptly  should,  therefore,  be  of  much  assis- 
tance in  controlling  the  insect  but  the  amount  of  labor  involved  in  carrying 
out  this  -plan  makes  it  impracticable  in  many  cases.  Cultivation  of  the  ground 
under  the  trees  has  proved  ineffective  and  allowing  poultry  and  hogs  to  run  in  the 
orchards  has  not  resulted  in  much  improvement. 

It  has  been  found  that  where  orchards  are  carefully  sprayed  just  about  the 
time  the  flies  appear,  using  slightly  less  arsenate  of  lead  than  the  standard  formula 
and  repeating  this  treatment  2  weeks  later,  excellent  results  are  obtained.  The 
addition  of  molasses  has  sometimes  been  advised,  but  comparative  tests  thus  far 
made  indicate  little  advantage  from  this  considering  the  extra  expense  and  trouble. 
To  know  just  when  to  apply  the  first  spray  is  a  difficulty  with  this  treatment, 
however,  and  it  has  been  suggested  that  owners  of  infested  orchards  can  place 
infested  apples  in  a  box  containing  several  inches  of  earth  and  leave  it  out  during 
the  winter.  In  the  spring,  cheese-cloth  can  be  placed  over  the  top  and  the  spray 
should  be  applied  as  soon  as  the  first  flies  are  seen  on  the  under  side  of  the  cloth. 

Family  Muscidae  (The  Muscid  Flies). — This  large  family  contains 
many  species  which  are  important  to  man  though  none  appear  to  be  crop 
feeders.  The  adults  range  from  small  to  medium  size  and  are  very 
abundant  in  most  cases. 

The  House-fly  (Musca  domesticaL.). — This  insect,  always  a  house- 
hold pest,  has  during  the  last  25  years  assumed  a  greater  importance 
to  most  people  because  of  the  discovery  that  it  is  a  carrier  of  a  number  of 
serious  human  disease-producing  agents,  among  these  being  the  germs 
of  typhoid  fever,  cholera,  dysentery,  etc. 

The  adult  flies  (Fig.  340)  hardly  need  any  description.  They  arc 
rather  small,  with  reddish-brown  eyes,  transparent  wings  and  blackish 
bodies.  Their  mouth  parts  are  for  sucking  and  a  "biting"  fly  found  in  a 
house  at  any  time  is  of  some  other  species. 

Winter  is  at  least  usually  spent  as  the  pupa  or  perhaps  in  some  cases 
as  the  larva.  As  the  weather  becomes  warm  in  the  spring,  the  flies 
emerge,  and,  in  temperate  regions,  begin  breeding  early  in  June,  though 
it  is  probable  that  in  warmer  climates  this  may  continue  throughout  the 
year.  Most  of  the  flies  breed  in  manure  piles,  particularly  those  exposed 
to  light,  but  almost  any  decaying  animal  or  vegetable  matter  may  be 
selected  for  the  purpose.  The  eggs  (Fig.  341)  are  laid  in  clusters,  about 
125  at  a  time  and  about  500  to  600  in  all.  They  hatch  in  from  8  to  12 
21 


322 


APPLIED  ENTOMOLOGY 


hr-  during  warm  weather  but  may  take  2  or  3  days  if  the  temperature 
is  low.  The  larvae  (Fig.  342)  feed  on  the  manure  or  other  material  in 
which  they  are  located,  for  a  varying  number  of  days  but  probably 
averaging  about  5  days.  Pupation  for  about  the  same  length  of  time 
follows,  but  many  of  the  maggots  may  leave  the  place  where  they  feed 
and  travel  a  short  distance  away  to  pupate.  Thus,  pupae  may  be  found 
in  the  ground  around  a  manure  pile  within  a  foot  or  two.  Pupation  is 
within  a  puparium,  the  fly  pushing  off  the  front  end  by  means  of  its 


FIG.  340. — House  Fly  (Musca  domestica  L.),  rather  more  than  twice  natural  size. 
duced  from  Hewitt:  The  House  Fly.} 


Rc- 


FIG.  341.  FIG.  342. 

FIG.  341. — Eggs  of  the  House  Fly,  much  enlarged.      (Original.} 
FIG.  342. — Full-grown  maggots  of  the  House  Fly,  much  enlarged.      (Original.} 

ptilinum.  After  the  emergence  of  the  adult  fly,  a  period  of  about  14 
days  elapses  before  egg  laying  begins  so  that  the  time  from  one  of  these 
periods  to  the  next  during  warm  weather  is  about  24  days.  From  7 
to  10  generations  are  liable  to  be  produced,  therefore,  in  a  long  season  in 
the  North  or  under  ordinary  conditions  in  the  South,  and  it  has  been 
calculated  that  the  descendants  of  a  single  fly  which  deposits  its  eggs 
the  middle  of  April  would  number  5,598,720,000,000,  by  the  middle  of 
September,  if  all  the  eggs  hatched  and  lived  to  adults  which  reproduced 
in  their  turn.  Fortunately,  this  is  not  actually  the  case,  eggs  failing  to 
hatch  and  many  larvae  never  reaching  maturity. 

House-flies  as  disease  carriers  are  of  extreme  importance.  Crawling 
over  and  feeding  upon  filth  of  any  kind,  their  legs  and  bodies  are  liable 
to  gather  the  germs  of  various  diseases,  which  may  also  be  taken  into  the 
flies  with  their  food.  Later,  visits  to  houses  and  human  food  over  which 


THE  DIPTERA  323 

the  flies  crawl  lead  to  leaving  some  of  the  germs  there,  and  the  well- 
known  habit  they  have  of  disgorging  some  of  the  food  already  eaten  and  of 
expelling  feces,  both  of  which  may  contain  the  germs  swallowed,  is  pretty 
certain  to  infect  the  human  food  over  which  they  crawl. 

Doubtless  many  of  the  microorganisms  thus  placed  on  food  are 
entirely  harmless  to  man  but  among  these  are  also  liable  to  be  those 
which  cause  diseases.  Milk  exposed  to  the  visits  of  flies  may  become 
infected  in  a  similar  way. 

Among  the  disease  germs  often  transmitted  thus  are  the  typhoid 
fevers,  anthrax,  tuberculosis,  cholera  and  yaws,  while  others  are  suspected 
of  being. carried  in  this  way  also.  The  habit  flies  have  of  visiting  spit- 
toons; of  alighting  on  sOres  on  persons  and,  in  fact,  of  crawling  over 
everything  where  disease  germs  are  liable  to  occur,  makes  them  par- 
ticularly dangerous  to  man.  It  should  be  noted,  however,  that  there 
seems  to  be  no  development  of  any  of  these  diseases  while  on  or  in  the 
flies  themselves,  the  insects  acting  as  passive .  carriers  only,  of  the  germs. 
The  relation  of  the  insect  to  the  disease,  therefore,  is  a  totally  different 
one  from  that  of  mosquitoes  and  the  diseases  in  which  they  are  concerned, 
where  the  disease-producing  organism  actually  passes  through  a  part  of 
its  life  cycle  in  the  insect. 

Control. — As  over  90  per  cent  of  the  house-flies  breed  in  manure, 
treatment  of  this  to  destroy  the  larvae  and  pupae  there  becomes  an 
important  line  of  attack.  But,  as  in  most  cases  this  manure  is  used  as 
fertilizer,  the  treatment  should  be,  if  possible,  something  which  will  not 
affect  the  value  of  this  material  for  use.  Most  of  the  larvae  live  near 
the  surface  of  the  manure  piles,  and  it  has  been  found  that  treatments 
with  materials  which  will  penetrate  six  or  eight  inches  into  the  piles  will 
reach  most  or  all  of  the  insects.  Three-quarters  of  a  pound  of  common 
borax  dissolved  in  3  gal.  of  water  and  poured  over  the  pile  will  be  suffi- 
cient to  properly  treat  10  sq.  ft.  of  surface  of  the  pile  to  the  depth  of  a 
foot,  so  that  applying  this  amount  of  fluid  to  15  sq.  ft.  should  reach  all, 
or  nearly  all,  of  the  larvae  and  pupae  in  this  space.  It  should  also  be 
applied  to  the  ground  around  the  pile  for  a  foot  or  two  as  many  of  the 
larvae  crawl  outside  the  pile  to  pupate. 

Too  much  borax  in  the  manure  injures  it  as  a  fertilizer,  and,  in  many 
cases,  it  is  better  to  use  Hellebore  instead.  Half  a  pound  of  this  in  10 
gal.  of  water  is  enough  for  10  cu.  ft.  or  to  cover  15  sq.  ft.  to  a  sufficient 
depth  to  reach  the  insects.  This  treatment  is  somewhat  more  expensive 
than  the  other  but  the  increased  value  of  the  manure  is  likely  to  more  than 
make  up  the  difference. 

Open  latrines  and  any  places  in  which  house-flies  are  breeding  should 
be  treated  to  destroy  the  larvae  and  pupae  present  or  covered  in  such  a 
way  as  to  prevent  the  flies  from  reaching  them.  Chloride  of  lime  and 
iron  sulfate  have  been  used  with  considerable  success  to  kill  fly  larvae 


324 


APPLIED  ENTOMOLOGY 


and  pupae  or  drive  away  the  adults,  particularly  when  sprinkled  around 
in  stables.  Hauling  the  manure  directly  to  the  fields  and  spreading  it 
there,  when  practicable,  preserves  more  of  its  value  than  letting  it  stand 
in  piles  where  leaching  and  other  processes  going  on  reduce  this.  The 
destruction  of  garbage  and  of  the  organic  matter  at  public  "dumps," 
in  which  flies  breed,  is  also  important.  Screening  houses,  food  and  gar- 
bage pails  or  cans  and  trapping  the  adult  flies  either  by  poisoned  or  sticky 
fly  papers  or  by  the  use  of  fly  traps  are  all  methods  for  reducing  the  fly 
pest  which,  when  these  insects  are  abundant,  should  be  made  use  of. 

Almost  any  fly  having  habits  similar  to  those  of  the  house-fly  may  be- 
come a  disease  carrier  in  a  similar  way,  and  the  above  methods  are  of 
value  against  them  all. 

Some  of  the  flies  in  this  family  lay  their  eggs  on  meat,  either  decaying 
or  fresh,  which  is  then  spoken  of  as  "  blown."  The  flies  which  do  this 
are  usually  the  ones  commonly  called  "  blue-bottle "  and  "  green-bottle " 
flies. 


m 


FIG.  343. — Screw- worm    Fly    (Chrysomyia    macellaria    Fab.),    greatly    enlarged.      (From 

U.  S.  D.  A.  Farm.  Bull.  857.) 


The  Screw-worm  Fly  (Chrysomyia  macellaria  Fab.). — This  pest  occurs  in 
South  America  and  northward  into  Canada.  It  is  a  serious  pest  to  live  stock  and 
other  animals,  chiefly  in  the  Southwestern  States,  though  occasionally  it  becomes 
important  farther  north  and  east. 

The  adult  fly  (Fig.  343)  is  of  a  dark  bluish-green  color  and  has  three  black 
stripes  along  its  back.  It  is  considerably  larger  than  the  house-fly.  Its  eggs 
are  laid  in  any  decaying  animal  matter  and  also  in  wounds  such  as  are  caused 
by  barbed  wire,  hooking,  etc.,  in  living  animals.  The  larvae  (Fig.  344)  hatch  in 
from  a  few  hours  to  a  day  or  two  and  burrow  into  the  tissues,  if  the  eggs  were  laid 


THE  DIPTERA 


325 


on  living  animals,  producing  an  irritating  substance.  The  action  of  this  and  the 
feeding  on  the  tissues  cause  the  animal  to  become  thin,  lose  its  appetite  and 
frequently  death  follows,  for  fresh  eggs  are  repeatedly  laid  in  the  same  wounds 
by  the  adults.  The  larvse  mature  in  4  or  5  days  in  living  animals  and  more 
slowly  in  dead  ones,  and,  on  becoming  full-grown,  drop  to  the  ground  which 
they  burrow  into  a  few  inches  to  pupate.  The  pupal  stage  lasts  from  3  days  to 
2  weeks  and,  at  the  end  of  this  time,  the  adult  flies  emerge,  completing  the  life 
cycle  in  from  1  to  4  weeks  according  to  the  conditions  of  the  weather. 


FIG.  344. — Full-grown  Screw-worm  Maggot,  greatly  enlarged. 

Bull.  857.) 


(From  U.  S.  D.  A.  Farm. 


Control. — Most  of  the  breeding  of  these  insects  is  in  dead  animals  and  there- 
fore all  carcasses  should  be  promptly  buried  or  burned.  To  protect  living  live 
stock,  efforts  to  prevent  their  injury  must  be  made  and  all  cases  of  injury  cared 
for  as  soon  as  possible.  This  may  be  done  by  pouring  a  little  chloroform  into  the 
wound.  It  is  then  generally  advisable  to  remove  the  maggots  and  clean  the 
wound  with  water  containing  5  per  cent  of  carbolic  acid.  Pine  tar  over  the  out- 
side at  the  wound  will  act  as  a  repellent  to  the  flies.  In  serious  cases,  the  services 
of  a  veterinarian  will  be  needed.  Tick  wounds  are  often  the  starting  points  for 
screw-worm  injuries,  and  ticks  should,  therefore,  be  controlled  as  far  as  possible. 

The  Tsetse  Flies  (Glossina  of  several  species). — These  Muscid  flies 
are  the  conveyers  to  man  of  the  dreaded  disease  known  as  "  sleeping 
sickness."  The  insects  occur  only  in  parts  of  Africa  where  they  are 
found  along  wooded  streams  and  where  large  game  animals  are  present. 
The  mouth  parts  of  these  flies  include  piercing  structures  and  the  insects 
normally  attack  the  wild  game,  but  man  is  also  liable  to  their  visits. 
The  disease  is  caused  by  a  Protozoan  animal  (Trypanosoma  gambiense) 
obtained  by  the  flies  while  feeding  on  infected  animals,  and  the  trypano- 
somes  may  be  directly  conveyed  into  another  animal  during  the  next 
day  or  two,  after  which  the  fly  becomes  innocuous  for  about  4  weeks: 
by  this  time,  those  of  the  parasites  which  entered  the  stomach  of  the  fly 
have  gone  through  a  development  in  the  body  of  the  insect  and  have 
gathered  in  the  salivary  glands.  The  fly  is  now  dangerous  for  about  3 
months.  In  man,  the  disease  appears  as  an  irregular  fever,  and  an  en- 
largement of  the  glands  followed  after  a  time  by  nervousness  and  sleep, 
the  patient  becoming  comatose  and  finally  dying.  The  earlier  stage  of 
the  disease  may  last  for  several  years  but  the  last  usually  continues  only 
from  4  to  8  months. 


326 


APPLIED  ENTOMOLOGY 


Thus  far  no  cure  for  the  disease  has  been  discovered  but  protection 
while  in  Tsetse  districts  can  be  obtained  by  screens,  veils,  gloves,  etc., 
and  by  keeping  away  from  the  localities  in  these  districts  where  the  flies 
occur.  Its  importance  is  indicated  by  the  estimate  that  in  10  years 
between  four  and  five  hundred  thousand  natives  died  from  this  disease. 
Another  species  of  trypanosome  carried  by  Glossina  flies  causes  the 
disease  of  domestic  animals,  particularly  horses  and  dogs,  known  as 
Nagana.  This  is  almost  always  fatal  to  these  animals. 

Family  Sarcophagidse  (The  Flesh  Flies,  Fig.  345). — This  is  a  large 
family  of  flies,  some  of  which  lay  their  eggs  on  dead  animals.     Others 

breed  in  manure,  decaying  matter 
and  similar  materials,  and  because 
of  these  habits,  there  is  always  the 
possibility  of  their  becoming  car- 
riers of  disease-producing  germs, 
though  as  they  seldom  visit  human 


FIG.  345.  FIG.  346. 

FIG.  345. — Adult  Sarcophagid  Fly  (Sarcophaga  sp.),  much  enlarged.  (From  U.  S. 
D.  A.  Farm.  Bull.  857.) 

FIG.  346. — Adult  Tachinid  Fly  (Tachina  mella  Walk.),  over  three  times  natural  size. 
(From  Britton,  Tenth  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1910.) 

food  in  houses,  the  chance  that  this  may  result  in  disease  is  much  less 
likely  than  in  the  case  of  the  house-flies. 

Family  Tachinidae  (The  Tachina  Flies). — This  family  has  by  some 
students  of  the  subject  been  regarded  as  the  most  useful  family  of  insects 
from  an  economic  standpoint,  its  larvae  being  parasitic  on  other  insects 
and  being  very  abundant.  .  This  estimate  of  their  importance  is  probably 
too  high  but  the  group  is  certainly  very  valuable  in  the  control  of  injurious 
forms.  The  adults  (Fig.  346)  somewhat  resemble  the  Muscidse,  but  the 
abdomen  is  liable  to  be  stouter  and  in  many  cases  bears  numerous  stiff 
bristles  which  are  very  noticeable.  The  eggs  (or  larvae  in  some  cases) 


THE  DIPTERA 


327 


are  laid  on  caterpillars  and  other  insects,  or,  in  some  cases,  on  the  leaves 
which  these  will  feed  upon,  and,  on  hatching,  the  maggots  bore  their 
way  into  the  host  and  feed  upon  its  tissues,  finally  killing  it.  The  adults 
are  common  around  flowers  and  also  in  places  where  plants  are  growing 
rankly,  and  there  are  many  species. 

Family  Anthomyiidae  (The  Anthomyiids) . — This  family  contains 
many  injurious  species,  the  larvae  of  some  mining  in  the  roots  and  of  others 
in  the  stems  and  leaves  of  important  crop  plants.  Others  breed  in 
decaying  vegetable  and  animal  materials  and  excrement  and  from  their 
habits  it  is  suspected  that  they  may  be  disease 
carriers  like  the  house-fly. 

The  Cabbage  Maggot  (Hylemyia  brassicce 
Bouche). — The  Cabbage  Maggot  is  a  native  of 
Europe  but  has  been  present  in  this  country 
for  many  years.  The  adult  (Fig.  347)  is  a  small, 
clear^winged  fly  about  two-tenths  of  an  inch  long, 
not  often  noticed  or  at  least  distinguished  from 
other  small  flies  present  in  the  fields.  Winter  is 
passed  as  the  pupa  in  its  puparium  underground, 
and  also  possibly  to  some  extent  as  the  adult,  in 
protected  places.  At  all  events,  the  adult  flies 
are  present  in  the  spring  as  soon  as  the  cabbage 


h 


FIG.  347.  FIG.  348. 

FIG.  347. — Adult  male  and  female  flies  of  the  Cabbage  Maggot  (Hylemyia  brassicce 
Bouche).  About  three  times  natural  size.  (After  N.  Y.  Agr.  Exp.  Sta.  Bull.  419.) 

FIG.  348. — Young  Cabbage  Plant  showing  Maggots  on  its  stem.  Natural  size. 
(Modified  from  Britton,  Fourteenth  Rept.  EnL  Conn.  Agr.  Exp.  Sta.  1914.) 

and  other  cruciferous  plants  are  available.  The  eggs  are  now  laid  on 
or  close  to  the  plants.  They  hatch  in  a  few  days,  and  the  maggots 
(Fig.  348)  attack  the  stem  just  below  the  level  of  the  ground  where 
they  feed  for  about  3  weeks,  lacerating  the  cell  walls  and  feeding  on 
the  softer  tissues,  using  for  the  first  process  a  pair  of  stout,  black 
hooks  attached  at  the  mouth  which  seemingly  are  extremely  modified 
mouth  parts.  When  full-grown,  the  larvae  leave  the  plants,  enter  the 
ground  and  form  puparia  from  their  larval  skins  within  which  they 
pupate  for  a  period  of  from  12  to  18  days  in  most  cases,  after  which  the 
adults  emerge  and  eggs  are  laid  for  a  second  generation. 


328  APPLIED  ENTOMOLOGY 

The  number  of  generations  in  a  season  has  been  worked  upon  by 
.  several  investigators  with  somewhat  differing  results.  It  seems  probable, 
however,  that  in  the  latitude  of  New  York,  the  insect  as  a  rule  has  three 
generations  though  in  favorable  seasons  four  are  possible,  and  in  unfavor- 
able ones  only  two  may  occur.  Presumably,  the  number  farther  north 
will  usually  be  two,  and  farther  south  four  may  prove  the  usual  number. 
Weather  conditions  apparently  have  an  influence  on  this — hot,  dry 
weather  hardening  the  roots  of  the  food  plants  so  that  feeding  is  slower 
than  would  otherwise  be  the  case,  and  this  same  kind  of  weather  also 
seems  to  lengthen  the  pupa  stage.  It  is  interesting  to  note  that  the 
insect  though  present  in  the  Gulf  States  does  not  seem  to  be  a  serious  pest 
south  of  the  latitude  of  southern  Pennsylvania.  It  has  been  found  as 
far  west  as  Colorado. 


FIG.  349. — Cabbage  Plant  protected  by  a  tar-paper  disk  around  its  stem.     (Modified  from 
Britton,  Fourteenth  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1914.) 

Whatever  the  number  of  generations  a  season,  the  insect  seems 
able  to  reach  the  pupa  stage  before  winter,  and  possibly  become  adult 
in  some  cases. 

The  Cabbage  Maggot  is  most  serious  as  a  pest  on  cabbages  and  cauli- 
flowers. It  also  attacks  turnips,  radishes,  mustard  and  other  cruciferous 
plants,  however,  and  late  generations  may  live  more  on  these  plants 
as  the  cabbage  and  cauliflower  roots  get  older,  tougher  and  less  attractive 
to  the  insects. 

Control. — Cabbage  and  other  plants,  liable  to  attack  while  in  seed- 
beds, can  be  protected  by  covering  these  places  with  screens  of  cheese- 
cloth. When  the  plants  are  set  in  the  fields,  tar-paper  disks  may  be 


THE  DIPTERA 


329 


placed  around  their  stems  close  to  the  ground  (Fig.  349)  and  usually 
give  good  results.  These  disks  may  be  cut  by  hand  from  ordinary  tar 
paper,  though  where  many  are  required,  the  use  of  a  cutting  stamp  is 
advantageous.  The  piece  is  usually  cut  six-sided  for  economy  of  the 
paper,  and  from  one  corner  a  cut  to  a  little  beyond  the  center  is  made 
and  also  a  short  cut  crossing  this  at  the  center,  giving  four  points  between 
which  the  stem  is  passed.  The  disk  is  then  pushed  down  to  the  ground. 
In  cultivating  later,  care  should  be  taken  to  brush  off  any  dirt  which 
gets  on  the  upper  side  of  the  disk  as  in  such  cases  the  fly  often  attacks 
the  plant.  The  destruction  of  all  the  refuse  of  the  plants  on  harvesting 
the  crop,  and  also  of  all  mustard  and  other  cruciferous  plants  near  by, 
is  desirable  to  prevent  further  increase  of  the  insect  there  before  winter. 

Various  other  treatments  have  been  suggested  but  have  not  given 
entire  satisfaction.  The  tar-paper  disks  are  not  entirely  effective  as 
protectors,  and  to  apply  them  carefully  requires  time,  but  they  give  the 
best  results  of  any  control  method  thus  far  discovered. 

Recently,  one  ounce  of  corrosive  sublimate  dissolved  in  10  gal.  of 
water,  poured  around  the  bases  of  the  plants,  has  given  quite  good  results. 


FIG.  350. — Adults  of  the  Onion  Maggot  (Hylemyia  antiqua  Meig.),  twice  natural  size. 
(From  Britton,  Eleventh  Rept.  Ent.  Conn.  Agr.  Exp.  Sta.  1911.) 

The  Onion  Maggot  (Hylemyia  antiqua  Meig.)  is  often  a  serious  pest, 
mining  in  the  bulbs  .and  quickly  causing  their  decay.  Like  the  Cabbage 
Maggot,  it  is  a  European  insect  but  has  been  known  in  the  United  States 
for  many  years  and  is  now  widely  distributed.  Details  of  its  life  history 
are  not  as  well  known  as  could  be  desired,  but  it  is  probable  that  the 
insects  pass  the  winter  as  pupae  and  perhaps  as  adults  also.  The  flies 
(Fig.  350)  lay  their  eggs  on  the  onions  soon  after  they  come  up  in  the 
spring,  and  these  hatch  in  a  few  days  forming  whitish  maggots  which 
attack  the  bulbs  and  feed  during  a  period  varying  according  to  weather 
conditions  for  from  2  to  4  or  5  weeks,  after  which  they  pupate  in  the 
ground,  or,  occasionally,  in  the  outer  layers  of  the  onion  itself.  During 
the  summer,  this  stage  continues  about  2  weeks,  after  which  the  adult 
flies  appear  and  in  about  10  days  begin  to  lay  eggs  for  a  second  generation. 

In  some  parts  of  their  range  there  are  probably  only  two  genera- 
tions a  year,  but  elsewhere  there  seem  to  be  three.  The  injury  caused 
by  this  insect  when  abundant  is  sometimes  large,  entire  fields  con- 


330  APPLIED  ENTOMOLOGY 

sisting  of  many  acres  having  nearly  every  onion  affected.  It  varies 
greatly  in  importance  in  different  years,  however,  there  being  in  some 
seasons  practically  no  maggots. 

Control. — The  adult  flies  feed  freely  both  before  and  during  the 
egg-laying  period.  Making  use  of  this  fact,  a  poisoned  bait  spray  issued, 
consisting  of  J^  oz.  of  white  arsenic  or  sodium  arsenate  dissolved  in  1  gal. 
of  boiling  water  to  which  is  then  added  from  ^  to  1  pint  of  strong- 
smelling  molasses.  This  is  sprayed  in  coarse  drops  in  strips  across  the 
field,  it  not  being  necessary  to  cover  the  entire  area  in  this  way.  Repeat 
twice  a  week  from  the  time  the  onions  show  until  the  middle  of  June. 
This  treatment  has  given  good  results  but  the  cost  of  the  labor  involved 
in  so  many  applications  is  considerable. 

Other  members  of  this  family  are  frequently  injurious,  and,  among 
these,  the  Seed-corn  Maggot,  often  attacking  peas  and  beans  also,  the 
Beet  and  Spinach  Leaf-miner  and  the  Radish  Maggot  may  be  mentioned. 
Methods  of  control  for  these  insects  are  at  present  far  from  being  as 
satisfactory  as  could  be  desired.  The  Lesser  House-fly  and  several 
other  small,  house-inhabiting  flies  which  belong  here  are  also  of  some 
importance  as  probably  being  disease  carriers. 

There  are  several  families  of  extremely  modified  aberrant  forms 
which  are  generally  classed  together  as  a  suborder  of  the  Diptera  called 
the  Pupipara.  Some  of  these  insects  are  winged  while  others  are  wing- 
less when  adult.  The  majority  of  them  suck  the  blood  of  birds  or  mam- 
mals though  one  species  not  thus  far  reported  from  America  is  found 
on  the  body  of  the  honey  bee.  Swallows  appear  to  be  favorite  hosts 
for  some  of  these  insects  and  bats  for  others,  while  the  most  familiar 
insect  belonging  here  lives  on  the  sheep  and  is  commonly  called  the 
Sheep  Tick.  A  number  of  others  of  the  group  are  also  wrongly  called 
ticks,  probably  because  of  their  color  which  is  similar  to  that  of  some 
common  ticks,  their  leathery  external  skin,  and  the  pla.ces  where  they 
are  found.  True  ticks  have  eight  legs,  however,  and  never  have  wings, 
while  six  legs  only  are  present  in  the  Pupipara  as  with  the  other  insects. 

The  Sheep  Tick  (Melophagus  ovinus  L.). — This  pest  of  sheep  is  a 
wingless,  brown  insect  about  a  quarter  of  an  inch  long.  It  occurs  in 
most  of  the  countries  where  sheep  are  raised  and  is  present  practically 
wherever  sheep  are  found  in  the  United  States,  though  most  abundant 
in  the  West  in  the  large  flocks.  The  adult  lives  in  the  fleece  of  the  host 
except  when  feeding,  at  which  time  it  moves  to  the  surface  of  the  skin 
of  the  animal,  punctures  it  and  sucks  the  blood  and  lymph  causing  irrita- 
tion which,  when  many  of  the  insects  are  present,  makes  the  sheep  rest- 
less, preventing  their  feeding  considerably,  and  resulting  in  their  failure 
to  grow  and  fatten  as  they  should. 

The  adult  (Fig.  351)  does  not  deposit  eggs,  these  being  retained  within 
the  body  of  the  parent  until  they  have  hatched  into  larvae  (Fig.  352)  and 


THE  DIPTERA 


331 


FIG.  351. — Adult  engorged  female  Sheep  Tick  (Melophagus  ovinus  L..),  greatly  enlarged. 
(From  Marion  Ines,  Bur.  An.  Ind.,  U.  S.  D.  A.  Farm.  Bull.  798.) 


FIG.  352. — Young  Sheep  Tick  just  after  emerging  from  its  puparium.     Greatly  enlarged. 
(From  Marion  Imes,  Bur.  An.  Ind.,  U.  S.  D.  A.  Farm.  Bull.  798.) 


332  APPLIED  ENTOMOLOGY 

during  this  period  being  nourished  by  the  secretions  from  glands  in  the 
body  of  the  parent.  When  the  development  of  the  larva  has  been  nearly 
completed,  it  leaves  the  parent  and  is  then  covered  by  a  soft,  white 
membrane  which,  after  some  hours,  turns  brown  and  hard  and  becomes  a 
puparium  within  which  the  animal  pupates  for  a  period  of  from  19  to 
24  days  after  which  the  adult  emerges.  After  about  10  to  14  days  more, 
their  first  pupae  appear.  A  pupa  is  produced  by  a  female  every  7  or  8 
days,  12  to  15  being  about  the  usual  number  in  all  per  individual. 

Control. — The  most  widespread  method  for  controlling  these  insects 
is  by  dipping  the  sheep  in  some  material  which  will  kill  the  ticks.  Some  of 
the  dips  used  for  this  purpose  are  coal-tar-creosote,  cresol,  nicotine  and 
lime-sulfur-arsenic.  Selection  of  the  best  dip  for  the  purpose  must 
be  determined  by  the  availability  of  soft  water,  ease  of  obtaining  the 
materials  and  other  local  factors.  In  general,  two  dippings  are  necessary 
and,  if  this  is  done  during  the  early  fall,  these  should  be  24  days  apart. 
Where  shearing  is  done  in  the  spring,  the  dipping  should  be  in  July  and 
August  unless  the  lambs  become  thickly  infested  soon  after  shearing,  in 
which  case  dipping  should  be  as  soon  as  the  shear  cuts  heal.  Many 
details  connected  with  dipping  make  it  necessary  to  become  thoroughly 
acquainted  with  the  process  before  treatment  is  actually  attempted, 
if  the  best  results  are  desired. 


CHAPTER  XXXII 
THE  SIPHONAPTERA 

The  Siphonaptera  or  Fleas  are  curious,  small  insects  ranging  from 
about  a  twentieth  to  a  sixth  of  an  inch  long.  They  are  evidently  related 
to  the  flies  in  many  ways  but  are  much  modified.  Most  of  the  members 
of  the  group  have  their  bodies  laterally  compressed  so  that  they  are 
narrow  (Fig.  353).  The  head  is  not  sharply  separated  from  the  body  and 
the  antennae  are  short  and  stout.  The  mouth  parts  are  for  piercing 
and  sucking,  and  modified  in  a  different  way  from  those  of  other  insects 
which  feed  in  this  manner.  While  the  identity  of  the  various  parts  has 


Fio.  353. — Adult   Cat   and    Dog    Flea    (Ctenocephalus   canis   Curtis),    greatly   enlarged. 

(Original.) 

not  been  conclusively  proven,  it  seems  probable  that  a  long  median 
pricking  structure  is  the  labrum  or  else  the  hypopharynx;  a  pair  of 
similar  structures  are  the  mandibles;  a  pair  of  rather  short,  stout  struc- 
tures at  the  sides,  each  with  a  palpus,  are  the  maxillae,  and  that  the 
labium  is  represented  by  a  rather  stout  basal  portion  bearing  two  long 
segmented  pieces,  perhaps  the  palpi,  so  shaped  as  together  to  form  a 
loose  sheath  for  the  piercing  parts.  Compound  eyes  appear  to  be 
absent. 

Backward-projecting  spines  occur  on  the  body,   largely  at  least, 
preventing  backward  movements  between  the  hairs  on  the  body  of  the 

333 


334  APPLIED  ENTOMOLOGY 

host  animal.  Rows  of  stout  spines  may  be  present  on  the  head  just 
above  the  mouth  or  on  the  pronotum  or  in  both  places.  These  are  called 
tsenidia  and  are  useful  in  identifying  the  species.  The  legs  are  long 
and  powerful.  Wings  are  absent  but  flat  scales  present  on  the  meso- 
and  metathorax  are  generally  regarded  as  their  rudiments.  The  larvae 
are  worm-like,  with  chewing  mouth  parts  and  pupate  within  a  cocoon. 

The  characters  distinguishing  these  insects  are: 

Insects  which  as  adults  have  their  bodies  strongly  compressed  sideways; 
are  without  wings  and  compound  eyes  but  have  legs.  Mouth  parts  for  pierc- 
ing and  sucking.  Larvce  worm-like.  Metamorphosis  complete. 

Adult  fleas  feed  entirely  upon  the  blood  of  mammals  and  birds, 
but  while  each  species  has  what  may  be  termed  its  preferred  host,  there 
seems  to  be  some  latitude  in  this,  and  other  animals  may  also  be  attacked. 

The  eggs  are  laid  loosely  among  the  hairs  of  the  host  and  drop  to 
the  ground  where  they  hatch.  The  larvae  which  are  slender,  whitish, 
and  rather  worm-like,  with  chewing  mouth  parts,  feed  on  decaying  vege- 
table and  animal  matter  for  a  period  varying  from  a  few  days  to  several 
months.  When  feeding  is  completed,  the  larva  spins  a  silken  cocoon  in 
which  it  pupates.  Here  it  may  remain  only  a  few  days  or  for  a  time 
which  may  be  more  than  a  year,  according  to  circumstances,  before 
emerging  as  the  adult.  The  adults  in  hot  weather  and  with  no  food  will 
live  only  a  few  days  but  when  food  is  available  they  may  live  a  month 
or  even  nearly  a  year.  Winter  in  the  North  is  usually  spent  in  one  or 
another  of  the  early  stages,  but  in  the  South  the  adults  may  be  present 
on  their  hosts  at  any  time. 

Hot,  dry  weather  is  not  favorable  to  the  rapid  breeding  of  these 
insects  but,  in  damp,  rainy  weather,  they  increase  rapidly,  particularly 
in  sandy  localities  as  the  moisture  there  is  more  uniform  where  the  early 
stages  live,  though  too  much  moisture  is  injurious  to  them. 

Fleas  are  mainly  household  pests,  coming  in  on  cats  and  dogs,  the  cat 
flea  being  the  most  common  generally,  though  in  the  West  and  South 
the  human  flea  is  also  abundant.  The  eggs  dropped  by  the  fleas  fall  to 
the  floors  and  the  larvae  feed  on  any  material  found  under  rugs  and  mat- 
tings, in  floor  cracks  and  similar  places,  and,  on  reaching  maturity,  attack 
the  fir"st  animal  they  can  reach. 

Various  animals  besides  those  already  mentioned  serve  as  hosts. 
Among  them  are  hogs,  poultry  and  other  birds.  Horses,  cattle  and 
sheep  are  not  often  attacked. 

Fleas  have  become  of  importance  to  man  aside  from  their  attacks  on 
his  person  with  the  discovery  that  they  may  carry  the  germs  of  the 
bubonic  plague.  This  much  dreaded  disease  with  its  high  mortality 
caused  by  Bacillus  pestis  occurs  in  rats'  blood,  and  by  feeding  on  this 
the  flea  brings  the  germs  into  its  own  body.  When  a  flea  attacks  a 
person,  it  often  ejects  partly  digested  blood  and  also  feces  near  the 


THE  8IPHONAPTERA  335 

"bite"  and  if,  while  the  wound  is  still  open,  this  place  is  rubbed  or 
scratched  the  germs  are  liable  to  thus  be  introduced  into  the  blood  of  the 
person.  Their  absence  from  the  mouth  parts  and  the  saliva  of  the  flea 
so  far  as  observations  have  yet  gone  indicates  therefore  that  inoculation 
with  the  germs  from  fleas  is  accidental,  but  as  most  persons  generally 
scratch  a  flea  bite,  it  is  at  least  frequent  enough  to  produce  many  cases 
of  the  disease.  In  California,  the  disease  has  also  been  found  in  ground 
squirrels  and  in  one  species  at  least  of  squirrel  flea  so  that  these  fleas  are 
also  a  menace  to  man. 

Control  of  Fleas. — In  houses,  flea  control  must  be  both  by  destroying 
the  adults  and  also  the  early  stages.  On  small  animals  which  are 
infested,  a  thorough  washing  with  a  soap  coal-tar  creosote  material 
used  as  a  " stock  dip"  of  which  a  number  of  kinds  are  for  sale  gives 
satisfactory  results  if  the  animal  is  thoroughly  scrubbed  and  partic- 
ular care  given  to  see  that  the  head — to  which  the  insects  collect  when 
the  animal  is  put  into  the  wash — shall  receive  particular  attention. 
Keep  the  animal  in  the  wash  for  five  to  ten  minutes.  If  it  has  a  tender 
skin,  this  treatment  may  be  followed  by  washing  in  warm  water  with 
soap. 

Other  ways  for  treating  infested  animals  are  by  rubbing  powdered 
naphthaline  into  the  hair,  or  by  dusting  thoroughly  with  Pyrethrum. 
Give  these  treatments  over  paper  on  which  the  stupified  fleas  fall  so 
that  they  may  be  gathered  and  burned.  Animals  which  are  attacked  by 
fleas  should  not  be  allowed  under  houses  as  is  so  often  the  case  in  the  South 
when  no  cellars  are  present  and  the  house  is  placed  on  low  posts.  In  such 
cases,  these  places  are  excellent  locations  for  fleas  to  breed  and  when  adult 
enter  the  houses. 

To  destroy  the  early  stages  successfully,  the  food  of  the  larvae  should 
be  kept  in  mind  and  all  such  material  be  removed.  Thorough  cleaning, 
removing  all  dust,  much  of  which  is  flea  food;  soaking  cracks,  where  it 
might  gather,  with  kerosene ;  airing  and  beating  rugs,  carpets,  straw  mat- 
tings and,  in  fact,  all  floor  coverings,  are  important  control  measures. 

There  are  other  ways  in  which  fleas  may  be  controlled.  One  is  to 
sprinkle  5  Ib.  of  flake  naphthaline  over  the  floor  of  an  infested  room  and 
close  tightly  for  24  hr. ;  then  open  and  sweep  it  into  any  other  room  needing 
treatment  and  manage  in  the  same  way.  Several  rooms  can  be  treated 
with  the  same  material.  Fumigation  with  sulfur,  using  4  Ib.  to  each  1,000 
cu.  ft.  of  space  if  the  young  are  present  and  2  to  3  Ib.  if  only  adult 
fleas  are  involved,  the  fumigation  to  continue  12  hr.,  is  also  a  successful 
control.  Cellars  infested  should  be  thoroughly  cleaned  and  whitewash 
used  freely. 

Flea  "bites"  if  troublesome  may  be  relieved  by  the  use  of  carbolated 
vaseline,  camphor,  or  a  3  per  cent  solution  of  carbolic  acid  in  water. 


336  APPLIED  ENTOMOLOGY 

One  of  the  fleas  commonly  called  the  "sticktight"  flea  (Echidnophaga  galli- 
nacea  Westw.)  is  a  rather  important  pest  of  fowls  in  the  South  and  Southwest, 
causing  trouble  as  far  north  as  Kansas.  These  fleas  gather  chiefly  on  the  heads 
of  the  birds  where  they  are  noticeable  around  the  eyes  and  on  the  wattles  and 
comb,  but  may  occur  elsewhere  on  the  animal.  Chickens  are  often  killed  by 
these  fleas  but  older  fowls  are  more  resistant.  This  flea  differs  from  most  other 
species  by  remaining  most  of  its  life  on  the  fowl,  whence  its  common  name. 

Where  the  infestation  is  severe,  the  use  of  carbolated  vaseline,  or  a  mixture  of 
lard  2  parts  and  kerosene  1  part,  carefully  applied  only  to  the  places  where  the 
fleas  are  on  the  fowl;  the  destruction  of  rats  which  also  harbor  this  pest,  and  a 
thorough  cleaning  of  the  poultry  houses  are  desirable.  Salt  on  the  soil  where  the 
fleas  are  breeding,  followed  by  a  liberal  application  of  water  by  sprinkling,  this 
last  repeated  two  or  three  times  a  week,  will  destroy  the  young,  but  no  salt 
should  be  left  for  the  poultry  to  feed  upon. 

One  species  of  flea  differs  somewhat  in  its  habits  from  most  of  these 
insects.  It  is  known  as  the  Chigoe  or  Jigger  flea  (Tunga  pene- 
trans  L.)  and  occurs  in  the  tropical  and  subtropical  portions  of  America 
and  also  in  Africa  and  India.  It  should  not  be  confused  with  a  tiny  mite 
(Class  Arachnida)  which  has  somewhat  similar  habits  and  is  found  as  far 
north  as  Massachusetts  and  Lake  Erie,  which  is  abundant  on  bushes,  and 
which  on  man  burrows  into  the  skin  causing  considerable  irritation. 


FIG.  354. — Chigoe  (Tunga  penetrans  L.) :  a,  an  Unfertilized  female;  b,  onefertilized, 
which  has  penetrated  the  skin  and  is  beginning  to  enlarge;  c,  one  enormously  enlarged 
by  the  development  of  eggs.  All  enlarged.  (From  Berlese.) 

The  Chigoe  is  found  on  domestic  animals,  birds  and  man.  The 
female  (Fig.  354a)  is  at  first  about  a  twenty-fifth  of  an  inch  long  but  its 
abdomen  may  later  become  as  large  as  a  small  pea.  The  adults  move 
about  but  when  the  female  has  been  fertilized  it  burrows  into  the  skin 
of  the  host  and  its  body  begins  to  enlarge  (Fig.  3546  and  c)  by  the  develop- 
ment of  eggs,  causing  a  painful  wound  like  an  ulcer.  The  eggs  are  expelled 
into  this  ulcer  or  may  fall  to  the  ground  but,  in  either  case,  hatch  in  a  few 
days,  and  those  in  the  wound  then  work  out  and  drop  to  the  ground. 

The  regions  usually  attacked  in  persons  are  the  bare  feet,  though  no 
part  of  the  body  is  entirely  free  from  the  danger  of  being  attacked.  Pus 


THE  SIPHON APT  ERA  337 

is  produced  in  the  wounds  and  when  many  of  the  fleas  are  present  the 
ulcers  may  run  together  and  cause  serious  results.  Protection  from  these 
pests  is  best  obtained  by  keeping  the  floors  clean,  using  naphthaline  as 
recommended  above;  cleaning  floors  and  walls  with  kerosene ;  and  wearing 
shoes  or  other  foot  coverings  to  keep  the  insects  from  reaching  the  skin. 
When  the  fleas  are  already  burrowing  they  may  be  removed  by  the  use  of 
a  needle  which  has  been  sterilized  by  passing  it  through  a  flame,  followed 
by  a  dressing  of  the  wound.  A  drop  of  turpentine  at  each  spot  attacked 
will  kill  the  fleas  and,  if  ulceration  has  not  gone  too  far,  the  wound  will 
generally  ulcerate  enough  more  to  expel  the  animal  and  then  gradually 
heal. 

Fleas  occur  in  nearly  all  parts  of  the  world,  and,  though  less  than  500 
kinds  are  known,  their  habits  and  their  relation  to  disease  make  them  an 
important  group  of  insects. 


CHAPTER  XXXIII 
THE  HYMENOPTERA 

The  insects  which  belong  in  this  large  order  have  no  general  common 
name,  but  many  of  them  are  well  known  as  bees,  ants  and  wasps.  The 
larger  portion  of  the  group,  however,  consists  of  small  insects  seldom 
noticed  except  by  those  looking  for  them. 

Most  Hymenoptera  have  wings  when  adult.  These  are  four  in  num- 
ber, membranous,  and  the  front  pair  is  the  larger.  They  have  rather  few 
cross  veins  as  a  rule,  and  in  some  cases  nearly  all  the  veins  are  missing. 
The  two  wings  on  the  same  side  of  the  body  are  united  by  a  row  of  hooks 
along  the  middle  part  of  the  costa  of  the  hind  wing,  which  catch  in  a  fold 
of  the  membrane  on  the  hinder  margin  of  the  wing  in  front,  the  two  wings 
in  this  way  acting  together  and  much  as  though  they  were  one.  The 
structures  uniting  them  are  called  the  frenal  hooks  or  hamuli,  and  the 
f renal  fold. 

The  body  in  insects  of  this  order  may  be  quite  large  and  stout,  as  in 
the  bumblebees;  or  long,  being  two  or  more  inches  in  length  in  some  trop- 
ical wasps,  but  most  of  them  are  much  smaller  insects  and  in  some  the 
body  may  be  only  about  a  fiftieth  of  an  inch  long  and  the  entire  animal 
almost  microscopic  in  size.  The  first  abdominal  segment  is  very  closely 
and  firmly  joined  to  the  thorax,  to  which  it  apparently  belongs.  In  a 
few  families  the  front  end  of  the  second  abdominal  segment  is  as  large  as 
the  rest  of  this  portion,  and  the  connection  between  the  first  and  second 
segments  is  full-sized,  but  in  most  of  the  groups  the  front  end  of  the  second 
segment  is  constricted  to  form  a  small,  stalk,  pedicel,  or  petiole  which 
connects  the  rest  of  the  abdomen  with  the  first  segment.  This  condition 
is  a  deceptive  one,  leading  to  the  idea  that  the  constriction  is,  as  is  true 
of  most  other  insects,  between  the  thorax  and  abdomen  rather  than  be- 
tween the  first  and  second  segments  of  the  latter.  The  first  segment, 
closely  joined  to  the  thorax  is  called  the  propodeum  or  median  segment. 
The  petiole  in  nearly  all  cases  joins  the  propodeum  close  to  the  lower  side 
of  the  body. 

Over  the  base  of  each  fore  wing  except  in  the  ants,  is  a  small,  arched 
scale  called  a  tegula,  which  roofs  over  the  place  where  this  wing  articulates 
with  the  body. 

In  the  female  Hymenoptera  an  ovipositor,  used  either  for  making 
holes  in  which  to  deposit  eggs,  or  modified  to  become  a  weapon,  is  almost 
always  present.  When  developed  for  its  original  purpose  as  an  organ 

338 


THE  HYMENOPTERA  339 

connected  with  egg-laying,  it  may  have  projections  along  its  lower  edge 
and  be  used  like  a  saw  to  cut  slits  in  leaves  or  other  structures  in  which 
to  insert  the  eggs.  In  other  cases  it  becomes  a  sort  of  boring  organ  used 
in  making  holes  in  leaves,  stems,  wood,  or  animals,  in  which  the  eggs  are 
placed.  Sometimes  the  ovipositor  is  very  prominent  and  is  not  retractile, 
while  in  other  species  it  can  be  drawn  entirely  within  the  body.  In  a 
large  section  of  the  order,  however,  regarded  as  containing  the  more 
highly  developed  members  of  the  group,  deposition  of  the  eggs  is  not 
within  objects  but  on  surfaces,  and  a  hole  being  no  longer  needed,  the 
ovipositor  has  become  modified  in  most  cases,  glands  connected  with  it 
produce  a.  more  or  less  poisonous  fluid  (possibly  it  is  more  or  less  poison- 
ous in  the  lower  forms  also)  and  the  sting  is  thus  produced,  a  structure  no 
longer  needed  for  its  original  purpose  having  been  transformed  into  a 
weapon  for  defense.  In  the  ants,  however,  various  degrees  of  reduction  of 
this  structure  occur,  some  ants  having  no  stinging  power  whatever  while  a 
few  are  quite  effective  in  this  way.  From  these  facts  the  reason  why  drone 
bees  and  the  males  of  the  other  Hymenoptera  are  harmless,  is  evident.  • 

The  two  sections  of  the  order  thus  distinguished,  are  called  the 
Terebrantia  or  boring,  and  the  Aculeata  or  stinging  Hymenoptera. 
Another  distinction  also  separating  these  divisions  may  be  seen  by  an 
examination  of  the  mouth  parts.  In  the  Terebrantia  these  are  quite 
typical  chewing  organs,  but  in  the.  Aculeata  the  maxillse  and  labium 
have  been  modified  to  form  organs  for  sucking  and  lapping  up  fluids, 
though  the  amount  of  this  modification  differs  in  different  families. 
A  third  distinguishing  feature  is  that  in  the  Terebrantia  the  hind  leg 
has  two  trochanters  while  in  nearly  all  the  Aculeata  there  is  only  one. 

Development  in  this  order  is  by  a  complete  metamorphosis.  The 
larvae  differ  much  in  appearance  in  the  various  families,  some  feeding 
on  leaves  and  greatly  resembling  caterpillars.  Others  are  borers  in 
wood  and  are  modified  to  adapt  them  to  life  under  such  conditions. 
Still  others,  particularly  those  which  are  parasitic  within  the  bodies  of 
other  insects,  may  be  so  changed  as  to  make  it  seem  almost  impossible 
that  they  can  be  insect  larvae.  Many  of  those  living  on  food  provided 
for  them  during  this  stage  of  their  existence  greatly  resemble  and  are 
sometimes  called  maggots.  At  pupation  a  marked  change  in  appearance 
takes  place,  antennae,  legs,  wing  stubs  and  body  characters  nearly  like 
those  of  the  adults  now  showing,  and  the  legs  and  antennae  project,  en- 
cased by  sheaths  of  the  pupa  skin,  the  pupa  in  this  order  being  a  pupa 
libera  as  already  described  for  some  beetles  (see  page  99,  and  Fig.  30). 

The  characters  by  which  Hymenoptera  may  be  recognized  are: 

Insects  which  when  adult  have  in  most  cases,  four  membranous  wings 
with  few  or  even  no  cross  veins,  the  hinder  pair  the  smaller.  Mouth  parts 
for  chewing,  or  for  chewing  and  also  for  sucking.  The  females  have  in  nearly 
all  cases  either  an  ovipositor  or  a  sting.  The  metamorphosis  is  complete. 


340 


APPLIED  ENTOMOLOGY 


The  Hymenoptera  are  important  from  an  economic  standpoint.  A 
rather  small  number  are  injurious,  destroying  crops  of  various  kinds 
but  the  majority  are. either  directly  or  indirectly  beneficial,  as  parasites 
of  destructive  insects,  or  by  aiding  in  the  fertilization  of  flowers,  and  in 
the  case  of  the  honey  bees  by  the  value  to  man  of  their  products. 

There  is  a  great  diversity  of  structure  in  the  order,  which  has  led 
to  the  establishment  of  many  families  which  fall  into  about  10  larger 
divisions,  generally  called  Superfamilies,  and  these  may  serve  as  the 
basis  for  more  detailed  consideration. 

Super/amity  Tenthredinoidea  (The  Saw-flies  and  Stem  Borers). — 
This  group  is  one  of  the  divisions  of  the  Terebrantia  as  already  described, 
its  members  having  no  constriction  of  the  abdomen.  Most  of  the  families 
belonging  here  are  leaf -feeders  and  their  eggs  are  usually  laid  in  slits  in 
the  leaves  sawed  by  the  ovipositors  of  the  adult  females.  Some  families, 
however,  have  the  ovipositor  constructed  for  boring  and  they  make 
holes,  either  in  herbaceous  or  woody  stems,  in  which  to  deposit  their 
eggs. 

The  plant-feeders  are  spoken  of  in  a  general  way  as  saw-flies  and  all 
are  injurious  to  the  plants  they  live  on,  though  of  course  many  of  these 

are  of  little  or  no  importance  to 
man,  but  a  few  injure  various 
crop-producing  plants. 

The  Currant  Worm  (Pteronidea 
ribesii  Scop.). — This  common  in- 
jurious saw-fly  is  a  native  of  Europe 
but  has  been  in  this  country  for 
many  years  and  is  widely  dis- 
tributed. It  feeds  on  the  leaves 
of  wild  and  cultivated  currants 
and  to  some  extent,  on  those  of 
gooseberries  also,  and  when  abund- 
ant the  plants  are  quickly  and 
thoroughly  stripped  of  their  foliage 

soon  after  it  develops,   which  checks  or  almost  entirely  prevents  the 
production  of  the  fruit. 

The  adult  saw-fly  (Fig.  355)  is  about  a  third  of  an  inch  long,  with  a 
pale  or  reddish-yellow,  rather  stout  body  with  blackish  spots.  It  passes 
the  winter  in  the  ground  within  an  oval  cocoon,  rather  papery  in  texture 
and  brown  in  color.  In  spring,  about  when  the  currant  leaves  become 
partly  developed,  the  adults  begin  to  emerge  from  their  cocoons  and  the 
females  lay  their  eggs  in  rows  on  the  leaves,  generally  along  the  veins  on 
the  underside.  The  larvae,  at  first  very  small  and  whitish,  feed  and  grow 
rapidly,  and  when  full-grown  are  nearly  three  quarters  of  an  inch  long, 
greenish  in  color  and  shaded  with  yellowish  at  both  ends.  During  the 


FIG.  355. — Currant  Worm  (Pteronidea 
ribesii  Scop.),  adult  and  larvae,  about  natural 
size.  (From  Minn.  Agr.  Exp.  Sta.  Bull.  84.) 


THE  HYMENOPTERA 


341 


intermediate  larval  instars  the  green  color  of  the  body  is  modified  by  the 
presence  of  many  black  spots.  After  feeding  from  2  to  3  weeks  the  larvae 
crawl  down  to  the  ground  and  pupate,  the  cocoons  resembling  those  al- 
ready described.  Adults  from  these  pupae  appear  in  late  June  or  July 
and  lay  eggs  for  a  second  generation,  and  in  some  cases  a  few  of  the 
insects  have  a  third  generation  before  winter.  The  second  and  third 
generations  (when  present)  do  not  attract  much  attention  generally,  as 
interest  in  the  currants  in  most  cases  ceases  for  the  season  with  the 
gathering  of  the  crop. 

Control. — Spray  the  currants  as  soon  as  the  leaves  have  developed 
or  as  soon  as  the  " worms"  appear,  with  arsenate  of  lead,  standard 
formula  or  a  little  weaker.  If  treatment  is  necessary  after  the  fruit 
has  begun  to  turn  red,  dust  fresh  hellebore  over  the  plants,  using  1  Ib.  of 
hellebore  thoroughly  mixed  with  about  5  Ib.  of  air-slaked  lime  or  flour. 
The  great  difficulty  in  controlling 
these  pests  is  that  the  adults  ap- 
pear and  lay  their  eggs  during  a 
rather  long  period  and  it  is  often 
necessary  to  spray  for  those  larvae 
which  appear  early,  before  all  the 
leaves  are  fully  developed.  Ac- 
cordingly, those  leaves  which  come 
out  after  the  spray  has  been  applied 
are  not  protected  and  larvae  ap- 
pearing afterwards  can  feed  on 
them  without  being  poisoned,  and 
a  second  spray  is  often  needed  on 
this  account. 


FIG.  356. — Pear  Slug  (Caliroa  cerasi  L.) : 
a,  adult;  b,  larva  with  slime  removed;  c, 
larva  from  above,  coveredby  its  slime;  d, 
leaf  showing  work  of  the  insect  and  with 
larvae  present:  a,  b  and  c  much  enlarged; 
d,  somewhat  reduced.  (From  Berlese, 

modified     from     U.    S.    D.    A.    Div.     Ent. 

Circ.  26.) 


The  Pear  Slug  (laliroa  cerasi  .L). 
—This  insect  feedson  the  leaves 
of  the  pear,  plum  and  cherry,  and 
though  a  native  of  Europe  is  now 
found  almost  everywhere  in  this 
country  (Fig.  356). 

The  adult  is  a  saw-fly  about  a  fifth  of  an  inch  long,  with  a  black  body.  It 
appears  after  the  leaves  develop  in  spring  and  lays  its  eggs  in  slits  sawed  in  the 
leaves,  forming  a  sort  of  blister  at  each  place.  The  larvae  soon  produce  a  dark- 
brown  glossy  slime  which  covers  them  and  conceals  their  true  outline,  making 
them  somewhat  similar  to  soft  snails  in  appearance.  They  feed  on  the  leaf  tissue, 
skeletonizing  it,  and  molt  four  times.  After  the  fourth  molt  the  slime  disappears 
and  the  larva  is  orange-yellow  and  does  not  feed.  It  now  passes  to  the  ground  in 
which  it  pupates.  A  second  generation  follows,  but  a  few  of  the  pupae  remain 
unchanged  in  the  ground  until  the  following  spring.  In  the  South  there  are  three 
generations,  at  least  in  some  cases. 


342 


APPLIED  ENTOMOLOGY 


Control. — Spraying  with  arsenate  of  lead,  standard  formula;  Nicotine  sulfate 
40  per  cent,  1  pt.  in  100  gal.  of  water,  with  3  or  4  Ib.  of  soap;  1  oz.  of  white  helle- 
bore in  3  gal.  of  water;  or  dusting  with  freshly  slaked  lime,  are  effective  treatments 
for  this  insect,  but  it  is  not  very  often  abundant  enough  to  call  for  the  use  of 
control  measures. 

A  similar  saw-fly  often  attacks  the  rose,  feeding  on  the  leaves,  its  dark-colored 
and  slimy,  though  small,  larvse  being  very  noticeable  when  abundant.  When 
treatment  is  necessary  the  methods  given  for  the  pear  slug  are  equally  effective 
with  this  insect. 

A  few  of  the  stem  and  wood  borers  in  this  superfamily  are  of  considerable 
importance,  but  most  of  them  are  seldom  noticed.  The  Wheat-stem  borer 
(Cephus  pygmceus  L.)  in  the  East  and  the  Western  grass-stem  borer  (Cephus 
cinctus  Nort.)  in  the  West  often  attack  growing  wheat.  The  adult  (Fig.  357) 


FIG.  357. — Western  Grass-stem  Borer  (Cephus  cinctus  Nort.):  3,  base  of  wheat  plant 
showing  larva  in  winter  position;  5,  adult  Saw-fly;  6,  full-grown  larva.  All  natural  size. 
(Modified  from  Can.  Dept.  Agr.  Ent.  Branch,  Bull.  11.) 


punctures  the  wheat  stem  in  the  spring  and  deposits  an  egg  inside  the  stalk  and 
the  larva  which  soon  hatches,  tunnels  in  the  stem  and  as  the  grain  ripens, 
works  its  way  downward,  and  by  harvesting  time  most  of  them  have  reached 
the  roots.  They  then  prepare  for  winter,  cutting  the  stalk  partly  off,  generally 
less  than  an  inch  above  the  surface  of  the  ground.  Each  now  plugs  the  cavity 
of  the  stem  below  this  point  for  a  short  distance,  leaving  about  half  an  inch  of 
space  between  the  plug  and  the  lower  end  of  the  cavity,  in  which  it  spins  a  cocoon. 
The  larva  winters  thus,  pupates  in  March  or  April  in  New  York  at  least,  and 
the  adult  appears  in  May.  The  life  .history  of  the  western  species  is  much  the 
same. 

Where  grass-seed  is  not  planted  with  the  wheat,  plowing  the  stubble  under, 
deeply,  at  any  time  between  harvest  and  the  following  May,  or  burning  the  stub- 
ble when  this  is  possible,  are  two  fairly  efficient  methods  of  control.  Where  it  is 
desired  to  lay  down  a  field  to  grass  and  the  insect  is  abundant  it  would  be  better 
where  practicable  to  use  oats  rather  than  wheat  with  the  grass-seed. 


THE  HYMENOPTERA 


343 


One  of  the  stem  borers  attacks  currant  stems.  The  adult  girdles  the  stem  after 
laying  its  egg,  and  the  larva  feeds  below  the  girdled  place,  which  shows  plainly, 
the  part  above  wilting  or  breaking  over.  Cutting  off  such  stems  as  soon  as  they 
are  seen,  eight  or  ten  inches  below  the  girdled  place,  will  control  this  insect. 

Most  of  the  borers  of  this  superfamily  which  tunnel  in  wood  are 
generally  called  Horn-tails,  the  straight,  stiff  ovipositor  somewhat 
suggesting  a  horn.  Various  trees,  both  deciduous  and  evergreen,  are 
attacked  by  different  species,  and  the  circular  exit  holes  of  the  borers 
after  they  have  become  adult  permit  the  entrance  of  moisture  and  the 
spores  of  fungi,  thus  providing  starting  places  for  decay.  Healthy, 
vigorous  trees  are  seldom  attacked,  but  the  death  of  others  is  hastened 

by    these    insects.      One    species      

known  as  the  Pigeon  Tremex 
(Tremex  columba  L.)  bores  in  the 
maple,  apple,  pear,  elm,  beech,  oak 
and  sycamore.  It  varies  from 
three-quarters  of  an  inch  to  twice 
as  much  in  length  (Fig.  358)  and 
its  body  is  cylindrical  and  nearly 
as  large  as  a  lead  pencil.  Its  color 
varies  from  nearly  black  with 
yellow  spots  on  the  abdomen  to 
yellow  with  some  black  marks. 
This  insect  is  often  noticed  on  the 
tree  trunks  during  the  summer 
months.  The  larva  tunnels  its 
course  through  the  wood,  going 

sometimes  several  inches  into  the  tree,  but  as  the  end  of  its  feeding 
period  approaches,  turns  outward  and  makes  a  hole  to  the  outside, 
leaving  only  a  thin  piece  of  bark  to  close  the  opening.  It  then  goes 
back  into  the  hole  a  short  distance  to  pupate  and  the  adult  on  emer- 
gence gnaws  away  the  piece  of  bark  and  escapes  from  the  tree.  An 
interesting  and  remarkable  looking  parasite  of  this  insect  will  be  considered 
later  in  the  chapter. 

Superfamily  Ichneumonoidea  (The  Ichneumon  Flies). — In  this  very 
large  and  important  group  the  insects  have  the  abdomen  constricted  as 
already  described,  between  the  propodeum  and  the  second  abdominal 
segment.  In  one  family  (the  Evaniidae  or  Ensign  flies)  of  rather  small 
insects  (Fig.  359)  the  petiole  of  the  second  segment  does  not  join  the  pro- 
podeum near  the  lower  side  of  the  body  but  near  the  upper  surface,  giv- 
ing these  insects  a  very  peculiar  appearance. 

The  Ichneumon  flies  (Fig.  360)  are  all  parasites,  attacking  Lepidop- 
tera,  Coleoptera,  Diptera,  and  some  Homoptera  ,Orthoptera  and  Hymen- 


FTG.  358. — Pigeon  Tremex  (Tremex  columba 
L.),  somewhat  reduced.      (Original.) 


344 


APPLIED  ENTOMOLOGY 


optera,  and  also  Spiders  in  their  early  stages,  at  least  in  most  cases,  and 
a  few  are  injurious  as  they  are  parasites  of  beneficial  forms.  Thus 
among  the  Coleoptera  parasitized  are  some  of  the  Lady  beetles.  In 
other  cases  it  is  the  parasites  themselves  which  are  parasitized.  In 
this  last  case  the  destruction  of  a  beneficial  parasite  by  another  makes 
the  latter  an  injurious  insect.  There  are  also  some  which  appear  to 
attack  the  parasites  of  the  parasites,  which  places  these  last  as  beneficial 
in  their  turn.  Primary  parasites  attack  non-parasitic  forms;  secondary 
or  hyperparasites  attack  primary  ones;  tertiary  parasites  attack  the 
secondary  ones,  etc. 


FIG.  359.  FIG.  360. 

FIG.  359. — An  Evaniid  (Brachygaster  minutus  Oliv.),  about    five  times  natural  size. 
(Modified  from  Kieffer.) 

FIG.  360. — Example  of  an  Ichneumon  Fly  (Ophion),  natural  size.      (Original.) 


The  importance  of  the  Ichneumon  flies  as  parasites  is  very  great  as 
they  are  abundant  and  destroy  enormous  numbers  of  injurious  forms 
each  year.  One  group  devotes  its  attention  to  plant  lice,  puncturing 
the  bodies  of  these  insects  and  laying  an  egg  in  each  puncture.  The 
tissues  of  the  plant  louse  are  fed  upon  by  the  parasite  and  the  body  of  the 
host  gradually  becomes  brown,  swollen  and  rather  globular,  and  it  dies, 
holding  on  to  the  place  where  it  was  feeding  at  the  time  of  its  death. 
After  pupation  within  the  body  of  the  host,  the  adult  parasite  cuts  a 
circular  opening  in  the  surface  of  its  host  and  escapes,  and  plant  lice 
bodies,  swollen,  brown,  and  with  a  hole  in  each  are  abundant  when  these 
insects  occur  in  large  numbers.  As  each  parasite  obtains  all  the  food 
necessary  for  its  entire  development  from  the  body  of  a  single  louse,  these 
insects  are  naturally  extremely  small  (See  Figs.  199  and  200). 

Another  Ichneumon  fly  which  is  often  noticed  has  a  body  an  inch  and 
a  half  or  more  long  and  an  ovipositor  often  over  three  inches  and  which  has 
been  recorded  in  a  few  cases  as  nearly  six  inches  in  length.  There  are  two 
kinds  of  about  this  size,  one  with  a  black  body  and  a  few  yellow  spots, 
the  other  brown  with  yellow  markings,  while  other  and  smaller  species 
also  occur.  These  insects  attack  the  Horn-tails  already  described  and 


THE  HYMENOPTERA  345 

may  often  be  seen  during  the  summer  on  trees  in  which  Horn-tail  larvae 
are  present.  These  Ichneumon  flies  are  called  the  "  Long-tailed  Thales- 
sas."  The  female  Thalessa  (Fig.  361)  crawls  about  over  the  trunk  of  a 
tree  which  in  some  way  she  discovers  is  infested  by  Horn-tails,  until  a 
satisfactory  place  is  found,  when  she  settles  at  that  point  and  begins  to 
force  her  ovipositor  into  the  bark  and  wood.  The  length  of  the  ovipositor 


FIG.  361. — Long-tailed  Thalessa  (Megarhyssa  lunator  Fab.):  a,  larva;  c,  pupa;  e,  adult 
female;  /,  side  view  of  abdomen  of  adult  female,  showing  attachment  of  ovipositor;  g,  adult 
male.  About  natural  size.  (Modified  from  Felt,  N.  Y.  State  Mus.  Mem.  8;  after  Riley.) 

is  suggestive  of  the  distance  it  must  be  pushed  in,  in  some  cases,  to  reach 
the  tunnel  of  the  Horn-tail  larva,  and  it  seems  almost  impossible  for 
such  a  slender  structure  to  be  forced  so  far  through  hard  wood.  When 
the  tunnel  of  the  Horn-tail  is  reached,  the  Thalessa  lays  an  egg  in  it  and 
then  draws  its  ovipositor  out  of  the  tree.  Sometimes  this  process  results 
in  the  death  of  the  Thalessa,  the  ovipositor  becoming  so  firmly  fixed 


346  APPLIED  ENTOMOLOGY 

in  the  wood  either  on  its  way  in,  or  during  the  withdrawal,  that  it  cannot 
be  removed  and  the  Thalessa  dies. 

The  egg  left  in  the  tunnel  of  the  Horn-tail  soon  hatches  and  the  larva 
travels  along  the  burrow  until  it  finds  the  borer,  to  which  it  attaches 
itself,  and  feeds  upon  its  juices.  It  is  probable  that  death  of  the  Horn- 
tail  is  not  permitted  as  a  result  of  this  feeding,  before  the  host  has  pre- 
pared an  outlet  to  the  surface  of  the  trunk  for  its  escape,  as  it  does  not 
seem  likely  that  the  adult  Thalessa  could  tunnel  its  way  out  successfully. 
Superfamily  Cynipoidea  (The  Gall  Insects). — This  group  of  small 
insects  (Fig.  362)  includes  species  having  very  diversified  habits,  but  the 
majority  of  them  pass  their  early  stages  within  abnormal  growths  on 

plants,  called  galls,  which  develop  in  connection 
with  their  presence.  Some  insects  other  than 
those  of  this  group  also  produce  galls,  particu- 
larly many  of  the  dipterous  family  Itonidida?, 
but  the  greater  number  of  the  more  noticeable 
galls  are  produced  by  Cynipids. 

The   cause  of  the  production  of  the  gall  has 
been  much  discussed,  some  investigators  claiming 

FIG.  362. — Example  of  a 

Gall  insect.  (Trigonaspis  that  at  the  time  the  female  insect  punctures  the 
megaptera  Pane.),  about  plant  for  egg-laying  she  also  injects  a  little 

twice  natural  size.    (Reduced 

from  Henneguy.)  poison  into  the  wound  which  stimulates  the 

plarit  cells  of  that  region  to  grow  in  an  abnormal 

manner.  But  the  general  belief  now  seems  to  be  that  the  larva  when 
it  hatches  gives  the  stimulus  for  this  abnormal  growth,  either  by  its 
presence  as  a  moving  body,  by  its  gnawing,  or  by  its  pouring  out  of 
irritating  fluids. 

The  gall  includes  either  one  larva  or  many,  according  to  the  species 
concerned.  It  stops  its  growth  about  the  time  the  larva  finishes  feeding, 
and  dries,  forming  a  protective  covering  within  which  the  insect  pupates 
and  escapes  subsequently  by  gnawing  its  way  out. 

In  some  species  such  an  adult  will  attack  a  totally  different  kind  of 
plant  from  the  one  it  itself  fed  upon  and  the  gall  produced  will  be  entirely 
different  from  the  other.  Adults  from  such  galls  will  deposit  their  eggs 
in  plants  of  the  first  kind,  however,  giving  us  a  series  of  generations  in 
which  two  different  kinds  of  plants  alternate  in  supplying  food.  This 
may  be  complicated  by  one  generation  consisting  only  of  females,  the 
other  evidently  being  derived  by  agamic  reproduction  (parthenogenesis). 

Galls  may  occur  on  roots,  stems,  twigs  or  leaves,  and  the  type  of  gall 
produced  is  always  the  same  on  any  one  kind  of  plant,  for  the  same  spe- 
cies (Fig.  363),  so  that  a  student  of  the  subject  can  tell  from  the  gall 
alone,  the  species  which  produced  it,  in  nearly  every  case:  one  found  on 
oak  leaves  is  nearly  an  inch  in  diameter,  globular,  with  a  parchment-like 
covering,  and  is  often  called  an  "oak  apple."  Within  the  outer  covering 


THE  HYMENOPTERA  347 

is  a  mass  of  radiating  fibers  and  at  the  center  a  small  cell  in  which  the 
insect  lives.  Protuberances  of  various  forms  on  the  leaves  of  many  kinds 
of  plants  are  produced  by  different  species  of  these  insects. 

Gall  insects  are  often  not  alone  in  their  habitations.  Some  members 
of  the  same  superfamily  as  the  gall-makers  are  frequently  found  in  the 
galls,  living  as  " guests,"  profiting  by  the  work  of  the  producers  of  the 
galls  but  not  injuring  them  in  any  way.  These  are  usually  called  in- 
quilines  and  often  greatly  resemble  their  hosts.  In  addition  to  the 
inquilines,  parasites  not  only  of  the  host  but  also  of  the  various  kinds  of 
inquilines  may  also  be  present,  adding  greatly  to  the  population  of  the 
gall.  Some  of  these  may  be  of  the  same  superfamily  as  their  hosts. 
Kieffer  lists  10  species  of  guests  and  41  species  of  parasites  which  he 
obtained  from  a  root  gall  on  oak,  besides  the  gall  maker  itself! 


FIG.  363. — Various  types  of  Galls,  about  natural  size.     (Original.) 

Galls  are  not  usually  of  any  great  economic  importance,  for  though 
they  may  injure  the  appearance  of  a  plant  or  tree  for  two  or  three  sea- 
sons, and  also  check  its  growth  somewhat,  the  abundance  of  parasites 
usually  stops  the  work  of  the  gall  makers  before  serious  injury  has  been 
accomplished. 

Superfamily  Chalcidoidea  (The  Chalcid  Flies) . — This  is  an  extremely 
large  group,  containing  thousands  of  kinds  of  insects,  most  of  which  are 
very  small,  and  a  few  are  only  about  a  fiftieth  of  an  inch  long.  Some  of 
them  live  in  galls,  parasitic  either  on  the  gall  maker  or  on  inquilines: 
others  are  parasitic  on  various  insects,  parasitizing  the  egg,  larva  or 
nymph,  pupa,  or  adult  according  to  the  species;  and  a  few  are  plant 
feeders  of  more  or  less  economic  importance.  The  wings,  except  in  some 
wingless  species,  have  very  few  veins,  the  most  prominent  one  running 
out  from  the  body  about  half  way  to  the  tip,  then  bending  forward  to  the 
costa,  after  which  it  bends  back  into  the  wing  a  short  distance  and  ends. 


348  APPLIED  ENTOMOLOGY 

This  is  the  only  one  in  a  great  many  cases,  though  a  few  other  weaker 
veins  are  often  present. 

The  plant  feeders  in  this  group  produce  small  galls  or  at  least  swellings 
of  the  portion  of  the  plant  where  they  live,  and  one  or  two,  by  attacking 
crop  plants,  are  of  importance  to  man.  A  number  of  species  of  the  genus 
Harmolita  attack  different  kinds  of  small  grains  such  as  wheat,  oats  and 
barley,  and  at  times  do  considerable  injury. 

The  Wheat  Straw-worm  (Harmolita  grande  Riley). — This  insect  extends  from 
New  York  to  Colorado  and  from  the  Great  Lakes  to  Virginia  and  Tennessee  and 
is  also  present  on  the  Pacific  Coast,  but  has  thus  far  been  of  little  importance  east 
of  the  Mississippi  River.  The  adult  is  a  tiny  black  insect  somewhat  resembling 
an  ant,  with  red  eyes,  and  legs  banded  with  yellow.  One  generation  has  wings; 
the  other  is  wingless. 

The  winter  is  spent  in  the  pupa  stage  in  the  stubble  of  wheat  fields  and  the 
adults  emerge  in  April  and  May  in  the  more  northerly  states;  earlier  in  the  South. 
These  are  the  wingless  forms  and  are  very  small.  They  lay  their  eggs  in  the 
wheat  plants  which  at  this  time  have  grown  only  a  short  distance  above  ground, 
and  the  larva  feeds  in  the  short  stem,  usually  producing  a  swelling  there,  and 
when  full-grown  it  has  worked  its  way  to  the  crown  of  the  plant  where  it  entirely 
consumes  the  head,  thus  preventing  the  formation  of  any  grain.  By  the  last  of 
May  these  larvse  have  completed  their  feeding  and  pass  through  a  brief  pupal 
period,  the  adults — winged  in  this  generation — emerging  in  early  May  in  the 
South,  and  in  June  in  the  North.  These  individuals  fly  freely  and  spread  to  other 
fields.  Eggs  are  now  laid  in  this  wheat,  preferably  well  up  toward  the  head 
where  the  joints  are  most  tender  and  juicy.  The  larvae  from  these  eggs  feed 
and  reduce  the  yield  of  wheat  by  consuming  nourishment  which  would  otherwise 
go  to  the  grain.  Full  growth  has  been  obtained  before  the  straw  hardens,  and 
pupation  occurs  during  the  fall.  Whether  the  insects  will  be  taken  off  in  the  straw 
or  remain  behind  in  the  stubble  depends  on  the  degree  of  advancement  of  the 
plants,  and  the  height  above  ground  of  the  cutting. 

Control. — Crop  rotation,  raising  no  wheat  on  the  same  land  for  2  years  in 
succession  is  a  good  treatment,  as  the  wingless  generation  cannot  migrate  to  other 
fields.  Volunteer  wheat  in  or  near  such  fields  should  of  course  be  destroyed  if 
the  rotation  is  to  be  most  effective.  Burning  over,  or  plowing  under  of  the 
stubble  is  also  desirable,  though  less  effective.  Winter  and  spring  wheat  should 
never  be  grown  near  each  other. 

The  Wheat  Joint-worm  (Harmolita  tritici  Fitch,  Fig.  364) . — This  is  a  species 
closely  related  to  the  last,  found  throughout  the  East  to  the  Mississippi  River  and 
south  to  about  the  same  limits  as  the  other  species.  Its  life  history  differs  from 
that  of  the  Wheat  Straw-worm  in  there  being  only  one  generation  a  year.  Winter 
is  passed  as  the  larva  in  wheat  straw  or  in  the  stems  of  various  grasses,  and  the 
adults  appear  in  May  or  June.  Eggs  are  deposited  as  high  up  the  wheat  stems 
as  the  adult  can  find  an  uncovered  stem.  The  larvse  have  completed  their  feeding 
by  harvest-time  but  do  not  pupate  until  the  following  spring.  Apparently  a 
rotation  of  crops,  and  care  that  waste  lands,  fence  borders,  etc.,  do  not  provide 
grass  stems  in  which  it  can  breed  and  winter  are  about  our  only  methods  for  the 


THE  HYMENOPTERA 


349 


control  of  this  pest.     The  injury  these  two  species  of  Harmolita  do  varies  all  the 
way  from  very  little  to  an  almost  entire  loss  of  the  crop. 

Where  clover  seed  production  is  extensive,  considerable  injury  to  the  crop  is 
often  caused  by  the  Clover-seed  Chalcid  (Bruchophagus  funebris  How.).     Red  and 


FIG.  364. — Adult  female  Wheat  Joint- worm   (Harmolita  tritici  Fitch),  greatly  enlarged. 
(From  U.  S.  D.  A.  Farm.  Bull.  1006.) 

crimson  clover,  and  alfalfa  to  some  extent,  are  attacked  by  this  tiny  insect  which 
feeds  as  a  larva  within  the  seed.  Another  species  works  in  a  somewhat  similar 
way  in  apple  seeds. 

A  Chalcid  whose  presence  is  essential  in  connection  with  the  produc- 
tion of  Smyrna  figs,  which  is  now  becoming  an  important  industry  in 
some  parts  of  this  country,  is  of  interest  for  that  reason.  This  insect, 


FIG.  365. — Fig  fertilizer  (Blastophaga  grossorum  Grav.).  A,  male,  about  fourteen  times 
natural  size;  B,  female,  about  ten  times  natural  size.     (Reduced  from  Henneguy.) 

known  as  Blastophaga  grossorum  Grav.  (Fig.  365),  and  its  relation  to  fig 
production,  are  well  described  by  Kellogg  as  follows: 

"The  male  Blastophagas  are  grotesque,  wingless,  nearly  eyeless  creatures 
which  never  leave  the  fig  in  which  they  are  bred,  but  the  females  are  winged  and 


350  APPLIED  ENTOMOLOGY 

fly  freely  about  among  the  trees.  A  fig  is  a  hollow,  thick,  and  fleshy-walled 
receptacle  in  which  are  situated,  thickly  crowded  over  the  inner  surface,  the 
minute  flowers.  The  only  entrance  into  the  receptacle  (or  fig)  is  a  tiny  opening 
at  the  blunt  free  end  of  the  young  fig,  and  even  this  orifice  is  closely  guarded  by 
scales  that  nearly  close  it.  The  eggs  are  laid  by  the  females  at  the  base  of  the 
little  flowers  in  certain  figs.  The  hatching  larvae  produce  little  galls  in  which 
they  lie,  feeding  and  developing.  They  pupate  within  the  galls,  and  the  wingless 
males  when  they  issue  do  not  leave  the  interior  of  the  fig,  but  crawl  about  over 
the  galls,  puncturing  those  in  which  females  lie,  and  thrusting  the  tip  of  the 
abdomen  through  the  puncture  and  fertilizing  the  females.  The  fertilized  winged 
female  gnaws  out  of  the  galls,  and  leaves  the  fig  through  the  small  opening  at  the 
blunt  free  end.  She  flies  among  the  trees  seeking  young  figs,  into  which  she 
crawls,  and  where  she  lays  her  eggs  at  the  bases  of  as  many  flowers  as  possible. 
But  it  is  only  the  wild,  inedible,  or  'caprifigs'  that  serve  her  purpose.  The 
flowers  of  the  cultivated  Smyrna  seem  to  offer  no  suitable  egg-laying  ground  and 
in  them  no  eggs  are  laid.  But  as  the  female  walks  anxiously  about  inside  the 
fig,  seeking  for  a  suitable  place,  she  dusts  all  the  female  flowers  with  pollen 
brought  on  her  body  from  the  male  flowers  of  the  caprifig  from  which  she  came, 
and  thus  fertilizes  them.  This  process  is  called  caprification.  Without  it  no 
Smyrna  fig  has  its  flowers  fertilized  and  its  seeds  'set.'  It  is  the  development 
of  the  seeds  with  the  accompanying  swelling  of  the  fleshy  receptacle  and  the 
storing  of  sugar  in  it  that  makes  the  Smyrna  fig  so  pleasant  to  the  palate.  The 
trees  may  grow  large  and  bear  quantities  of  fruit,  but  if  the  fig  (really  the  fig- 
flowers)  are  not  caprified,  the  size,  sweetness,  and  nutty  flavor  of  the  perfect 
fruit  are  lacking.  To  insure  caprification,  branches  laden  with  caprifigs  con- 
taining Blastophagas  just  about  to  issue  are  suspended  artifically  among  the 
branches  of  the  Smyrna  fig.  Of  course  the  female  Blastophaga  entering  a 
Smyrna  fig  and  dying  there  leaves  no  progeny,  for  she  lays  no  eggs.  It  is  there- 
fore necessary  to  maintain  a  plantation  of  caprifigs  in  or  near  the  Smyrna  orchard. 
These  bear  three  crops  or  generations  of  figs :  one,  the  '  profichi,'  ripening  in  the 
spring;  another,  the  'mammoni/  ripening  in  the  late  summer;  and  the  third, 
or  'mammae'  generation,  which  hangs  on  the  tree  through  the  winter.  By 
means  of  these  successive  generations  of  caprifigs  a  series  of  three  generations 
(or  sometimes  four)  of  Blastophaga  appear  each  year." 

The  great  importance  of  the  Superfamily  Chalcidoidea  to  man  does 
not  rest  either  upon  the  importance  of  its  destructive  members  or  upon 
the  Blastophaga,  but  on  the  enormous  number  of  parasitic  forms  included 
in  the  group.  These  work  in  various  ways  as  has  already  been  indicated, 
but  only  one  can  be  considered  here.  It  is  a  parasite  on  various  species 
of  butterflies,  particularly  the  Cabbage  butterflies,  and  is  known  as 
Pteromalus  puparum  L.,  having  no  common  name. 

This  insect  (Fig.  366)  is  probably  a  native  of  Europe.  It  was  noticed 
here  about  1870  and  is  now  present  wherever  its  host  insects  occur  and 
frequently  destroys  great  numbers  of  them. 

The  adult  has  a  green  body  about  a  tenth  of  an  inch  long.  The 
female  punctures  the  chrysalids  of  the  host  and  lays  her  eggs  within  the 


THE  HYMENOPTERA 


351 


body,  in  these  punctures,  and  the  larvae  which  hatch  from  the  eggs  feed 
upon  the  chrysalis,  finally  killing  it  about  the  time  they  become  full- 
grown.  They  then  leave  the  chrysalis  and  spin  small,  white  cocoons, 
usually  in  a  rather  compact  mass  somewhere  near  what  remains  of  their 
deserted  host,  emerging  from  these  cocoons  after  a  time,  as  adults  which 


FIG.  366. — Pteromalus  puparum  L.,  a  Chalcid  parasite  of  the  Cabbage  Worm  and 
other  insects:  male  (left),  and  female  (right).  Hair  lines  show  the  natural  size.  (After 
Chittenden,  U.  S.  D.  A.) 

start  another  generation.  It  has  been  discovered  that  egg-laying  in  this 
species  (and  in  many  other  parasites  also)  may  continue  during  quite  a 
long  period  provided  the  adult  can  obtain  food,  and  this  in  many  cases  at 
least  is  accomplished  by  puncturing  the  body  of  the  insect  in  which  eggs 
are  to  be,  or  have  just  been  laid,  and  feeding  on  its  juices. 

Super/amity  Serphoidea. — This  superfamily,  long  known  as  the 
Proctotrypoidea,  contains  a  large  number  of  insects,  nearly  all  very 


FIG.  367. — Pelecinus    polylurator    Dru.:  a,    female;    6,    male.     Natural    size.      (Original.) 

small,  and  most  of  them  parasitic  on  other  insects  or  on  spiders.  Para- 
sitism of  insect  eggs  seems  to  be  very  frequently  the  habit  in  the 
group.  Some  of  the  forms  attacked  by  this  group  are  Hemiptera, 
Diptera,  Orthoptera,  Lepidoptera,  Neuroptera  (Aphis  lions)  and  Cole- 
optera,  and  some  are  found  in  ants'  nests,  parasitic  on  these  insects. 
None  of  the  members  of  the  Superfamily  is  liable  to  attract  the  attention 
of  those  not  entomologists,  with  one  exception,  an  insect  known  as  the 
Long-tailed  Pelecinus  (Pelecinus  polyturator  Drury),  the  female  (Fig.  367a) 
of  which  has  along,  slender  body  often  between  two  and  three  inches  long, 


352  APPLIED  ENTOMOLOGY 

and  glossy  black  in  color.  The  extremely  long  abdomen  of  this  insect 
which  in  flight  is  generally  carried  partly  curled  up  beneath  it,  and  its  odd 
appearance  also  when  at  rest,  sometimes  cause  it  to  be  noticed  and  the 
remark  made  that  it  must  be  a  dangerous  animal.  This  is  not  the  case, 
however,  as  the  insect  is  harmless.  It  is  a  parasite  on  June  bug  larvae 
which  it  evidently  seems  to  hunt  for  in  the  ground  and  it  is  particularly 
abundant  in  sandy  localities.  The  writer  has  seen  over  80  of  these 
insects  resting  on  fences,  walls  and  elsewhere  in  the  course  of  a  single 
early  morning  walk  in  the  streets  of  Nantucket,  the  distance  covered 
being  not  over  four  city  blocks.  The  male  (Fig.  3676)  which  is  extremely 
rare  or  at  least  seldom  seen,  has  a  short,  club-shaped  abdomen  and  is 
about  an  inch  long. 


A  general  survey  of  the  habits  of  the  parasitic  groups  of  the  Hymenop- 
tera  reveals  several  diversities  of  life  and  habits  worthy  of  being  presented 
together.  In  the  first  place  all  stages  of  the  host  may  be  subject  to 
parasitic  attack.  The  egg  seems  to  be  selected  in  some  cases  and  the 
pupa  or  the  adult  in  others:  larvae  however  appear  to  be  particularly 
liable  to  be  parasitized.  Where  the  egg  stage  is  the  one  endangered, 
the  parasite  may  consume  its  host  before  the  latter  can  develop  to  the 
point  where  it  is  ready  to  hatch,  thus  preventing  any  injury  whatever 
if  the  host  be  an  injurious  species.  In  other  cases  the  host  though  para- 
sitized is  able  to  complete  its  embryonic  development,  hatch,  and  feed 
for  a  time  as  a  larva  before  it  concedes  victory  to  the  parasite  feeding 
within  it  and  dies.  In  the  case  of  larvae  the  parasitism  may  cause  the 
death  of  the  host  before  it  becomes  full-grown,  or  the  latter  may  pupate, 
but  progress  no  farther.  Pupae  parasitized  are  destroyed  before  becoming 
adult  and  adults  attacked  may  or  may  not  be  able  to  live  until  they 
reproduce. 

These  various  relations  of  parasite  and  host  have  a  bearing  on 
the  effectiveness  of  the  parasite.  In  the  majority  of  cases  it  is  the 
next  generation  which  is  cut  off,  most  of  the  injury  normally  caused 
by  the  host  concerned  being  done  before  the  parasite  stops  it,  except 
in  the  case  of  the  egg  parasites  which  destroy  the  host  before  it  hatches. 
Egg  parasites  of  this  kind  therefore,  are  generally  regarded  as  the  most 
beneficial,  though  the  great  numbers  of  the  other  forms  make  their  work 
very  effective. 

Sometimes  one  parasite  only,  feeds  upon  its  host.  In  other  cases 
there  may  be  many,  as  with  some  of  the  Ichneumonoidea,  where  in  one 
instance  over  1,200  were  bred  from  a  single  caterpillar.  It  would  seem 
that  the  parent  parasite  is  able  to  calculate  the  amount  of  food  furnished 
by  a  host  and  deposit  only  a  sufficient  number  of  eggs  to  correspond  with 
the  food  supply.  The  more  probable  explanation,  however,  is  that 


THE  HYMENOPTERA 


353 


parasites  laying  many  eggs  regularly  attack  only  those  species  of  insects 
large  enough  to  provide  for  the  progeny,  while  those  which  lay  only  one 
egg  in  or  on  a  host  require  all  the  food  provided  there  for  the  single 
parasite.  No  case  is  known  where  a  parasite  normally  laying  many  eggs 
in  a  host  will  select  a  smaller  one  and  deposit  only  one  or  a  few  in  it. 


FIG.  368. — Hawk-moth  larva  with  cocoons  of  parasites  which  have  fed  upon  it,  on  its  back. 
(From  Felt,  N.  Y.  State  Mus.  Mem.  8.) 

Variations  in  the  location  of  the  pupa  also  occur.  Some  parasites 
pupate  within  the  body  of  the  host;  others  on  its  surface  (Fig.  368)  while 
still  others  leave  the  insect  entirely,  pupating  singly  or  in  groups,  away 
from  it.  Tomato  worms  and  other  large  caterpillars  are  often  seen  in 
the  fall,  either  dead  or  dying,  and  with  many  small,  white,  oval  bodies 
on  their  backs.  These  are  cases  where  the  numerous  parasites  after 
having  completed  feeding  within  the  body  of  the  host,  have  come  out  and 
pupated  on  its  back,  the  white  bodies  being  the  cocoons  of  the  parasites. 


Superfamily  Chrysidoidea  (The  Cuckoo  Wasps). — This  is  a  rather 
small  group  of  the  Hymenoptera,  the  insects  (Fig.  369)  being  seldom  over- 
half  an  inch  in  length  and  generally  considerably 
smaller.  Their  bodies  are  green,  of  a  metallic  or 
bluish  shade  which  quickly  distinguishes  them 
from  certain  of  the  bees  which  are  also  green 
but  brighter.  The  surface  of  the  body  is  gen- 
erally closely  covered  with  fine  indentations 
which  give  it  a  roughened  appearance. 

These  insects  are  able  to  sting  but  no  poison 
gland  seems  to  be  present.     The  abdomen  which 
has  only  a  few  (three  to  five)   visible  segments,  is  flat  beneath,  and 
when  attacked  the  insect  can  roll  itself  into  a  ball  for  protection. 

The  Chrysids  are  parasitic,  chiefly  on  wasps  and  bees,  though  a 
few  are  claimed  to  attack  saw-flies  and  one  is  a  parasite  on  the  Oriental 
Moth.  The  parent  Chrysid  watches  its  opportunity  to  visit  the  nest  of 
its  host  and  lays  an  egg  in  a  cell  with  that  of  the  host.  On  hatching 

23 


FIG.  369.     Cuckoo  Wasp 

(Chrysididae) ,         somewhat 
enlarged.     (From  Bischoff.) 


354 


APPLIED  ENTOMOLOGY 


the  larva  of  the  Cuckoo  Wasp  may  eat  the  host  or  it  may  consume  the 
food  stored  there,  thus  starving  the  proper  inmate  of  the  cell.  Adult 
bees  and  wasps  know  these  enemies  of  their  young  and  sometimes  drive 
them  away  from  their  nests,  though  frequently  without  success,  the  Cuckoo 
Wasp  watching  its  chance  to  return  later  unobserved.  Taking  into  con- 
sideration the  nature  of  the  hosts  of  the  Chrysids  it  is  probable  that  as 
a  whole  the  group  should  be  considered  injurious  rather  than  beneficial. 

Superfamily  Sphecoidea  (The  Digger  Wasps). — The  insects  of  this 
group  vary  much  in  size,  some  being  very  small  while  others,  particularly 
tropical  species,  may  be  more  than  an  inch  and  a  half  long.  Some  of 
them  are  bright-colored,  yellow,  orange,  green  and  black  being  the  more 
usual  colors,  and  the  wings  are  frequently  smoky  and  with  an  iridescent 
luster.  A  functional  sting  is  present. 


FIG.  370.  FIG.  371. 

FIG.  370. — Bembecid  Wasp  (Bembidula  quadrifasciata  Say),  natural  size.      (Original.) 
FIG.  371. — Sphccid  Wasp  (Sceliphron  ccemcntarium  Dm.),  natural  size.      (Original.) 

Some  of  the  insects  (Fig.  370)  in  this  superfamily  (Families  Bembecidse 
and  Cerceridse)  have  the  petiole  connecting  the  mass  of  the  abdomen 
with  the  propodeum  very  short,  but  in  the  others  (Fig.  371)  it  is  long  and 
slender,  the  entire  first  segment  behind  the  propodeum  and  sometimes 
a  part  of  the  second  being  very  slender  and  elongate.  These  insects  are 
often  spoken  of  as  the  " thread- waisted  wasps." 

The  digger  wasps  are  all  solitary  in  their  habits.  The  females  of 
many  species  dig  holes  in  the  ground,  in  some  cases  several  inches  deep: 
others  dig  out  the  pith  in  plant  stems:  still  others  make  nests  of  mud, 
gathered  where  there  is  moist  earth,  placing  them  under  projecting 
stones,  under  eaves  of  buildings  or  in  houses  where  access  is  easy  through 
open  doors  or  windows:  in  some  species  the  nest  is  excavated  in  wood, 
and  a  few  kinds  have  either  not  developed  the  nest-making  habit  or  have 
lost  it  and  use  holes  or  the  deserted  nests  of  other  species  for  themselves. 
In  many  instances  the  nest  is  subdivided  into  chambers  separated  from 
each  other  by  partitions  of  mud. 

Wherever  the  nest,  and  whatever  the  material  which  composes  it, 
its  purpose  is  the  protection  of  the  young  of  the  insect  and  of  the  food 


THE  HYMENOPTERA  355 

which  is  stored  there.  After  constructing  the  nest,  either  by  digging, 
building,  or  otherwise,  the  parent  starts  out  to  provision  it.  The  food 
differs  with  different  species.  Some  take  certain  species  of  grasshoppers, 
others,  flies:  Homoptera,  Hemiptera,  Hymenoptera,  Lepidoptera  larvae, 
some  Coleoptera,  and  Spiders,  are  also  listed  as  the  prey  of  digger  wasps 
of  various  species. 

When  one  of  the  wasps  finds  an  insect  of  the  desired  kind  she  attacks 
and  stings  it,  generally  not  killing,  but  only  partly  paralyzing  it  and  ap- 
parently chiefly  the  locomotor  centers,  so  that  it  cannot  escape.  The 
prey  is  then  grasped  by  the  wasp  and  carried  to  the  nest.  In  some  cases 
flight  is  possible  to  the  wasp  carrying  this  load,  but  in  many  cases  the 
prey  is  far  too  heavy  for  transfer  in  this  way,  at  least  in  the  case  of  those 
wasps  which  burrow  in  the  earth,  and  it  is  therefore  dragged  along  the 
ground  to  the  nest.  How  the  wasp  knows  the  direction  to  take  and 
how  finally  to  locate  the  hole  it  is  practically  impossible  to  determine, 
but  in  most  cases  the  insect  seems  to  have  little  difficulty. 

Once  arrived  at  the  nest  the  prey  is  dragged  into  it  and  if  it  alone 
provides  a  sufficient  food  supply  for  the  young  wasp  to  be  developed 
there,  the  parent  now  lays  an  egg  on  it  and  then  closes  up  the  opening 
of  the  nest.  In  the  case  of  nests  in  the  ground  this  is  accomplished  by 
scratching  in  dirt  from  around  the  hole  and  packing  it  in  firmly.  In 
three  or  four  cases,  species  of  the  wasp  genus  Sphex  have  been  seen  by 
different  observers  to  pick  up  a  tiny  pebble  with  their  mandibles  and, 
using  it  like  a  hammer,  pound  down  more  firmly  the  earth  filled  into  the 
hole.  This  may  perhaps  be  interpreted  as  representing  the  "Stone 
Age"  in  the  development  of  insects! 

If  the  single  insect  captured  will  not  provide  enough  food  for  the 
young  wasp,  the  parent  proceeds  to  bring  in  more,  until  sufficient  has 
been  supplied,  after  which  the  opening  is  closed  and  another  nest  or 
cell,  according  to  the  kind  of  wasp  concerned,  is  begun.  In  a  few  species 
the  prey,  instead  of  being  paralyzed,  appears  to  be  killed  and  it  is  claimed 
that  the  wasp  brings  fresh  supplies  of  food  from  day  to  day  for  the  food 
of  its  young. 

Detailed  studies  on  the  lives  and  habits  of  these  wasps  have  been 
recorded  by  many  observers,  and  the  remarkable  traits  these  insects 
possess  form  one  of  the  most  interesting  topics  in  Entomology. 

One  species  (Fig.  372)  deserves  particular  attention  because  of  its 
singular  ways.  It  is  a  large  wasp  often  called  the  Cicada-killer  (Sphecius 
speciosus  Drury)  its  body  being  over  an  inch  long,  its  abdomen  black  with 
yellow  marks.  It  is  found  over  a  large  portion  of  the  United  States  and 
appears  during  the  dog-days  in  summer.  It  makes  its  nests  in  the  ground 
and  provisions  them  with  adult  dog-day  cicadas  (Homoptera),  larger 
and  heavier  than  itself,  which  it  catches  in  the  trees.  The  prey  cannot 
be  carried  to  the  nest  by  flight  but  the  wasp  starts  from  the  point  of 


356 


APPLIED  ENTOMOLOGY 


FIG.  372. — Cicada-killer  (Sphedus  speciosus 
Dru.),  about  natural  size.      (Original.) 


capture  with  its  paralyzed  prey  and  flies  as  far  as  possible  before  striking 
ground.  It  has  been  claimed  that  at  times  the  wasp  drags  the  cicada 
up  trees  or  bushes  several  times  en  route,  in  order  to  gain  elevation  for  a 
fresh  start  toward  its  nest.  The  nests  themselves  may  branch  under- 
ground several  times,  each  having 
a  terminal  chamber  for  the  recep- 
tion of  one  or  two  cicadas  and  an 
egg  of  the  wasp. 

Superfamily  Vespoidea  (The 
Social  Wasps).  — This  common 
name  for  the  Superfamily  is  mis- 
leading, as  a  number  of  families 
included  here  do  not  live  in  colonies, 
but  no  other  term  at  present  ap- 
plied to  the  group  is  at  all  ex- 
pressive, and  some  at  least  of  the 
insects  included  are  colonial  in 
their  habits. 

Some  of  the  Vespoids  are  very 
small,  being  less  than  a  sixth  of  an 
inch  long,  while  others  found  in 

the  tropics  measure  more  than  two  inches,  their  bodies  having  a  bright 
blue  luster,  and  with  orange  or  yellow  wings.  Forms  present  in  the 
United  States  except  in  the  South  and  Southwest  are  smaller,  some 
having  bodies  marked  with  black  and  yellow.  The  families  included 
in  the  group  differ  much  in  appearance  and  in  habits,  and  it  is  probable 
that  further  study  will  result  in  the  .group  being  dismembered  and 
several  Superfarnilies  being  formed  instead  of  one. 

Some  of  the  Vespoids  are  solitary,  dig  nests  in  the  ground  which 
they  stock  with  spiders,  and  perhaps  with  some  kinds  of  insects:  others 
are  parasites,  some  of  the  insects  attacked  being  beetle  larvae  and  cater- 
pillars, but  in  these  a  nest  to  which  the  prey  is  taken  does  not  seem  to  be 
formed,  an  egg  of  the  wasp  being  laid  on  its  host  wherever  it  is  found,  and 
the  wasp  larva  feeding  there.  Some  appear  to  be  parasites  on  bees  and 
wasps,  living  in  the  cells  of  the  bees  and  feeding  on  their  young.  Still 
others  are  not  parasites  but  feed  on  honey,  pollen,  etc. 

In  one  family,  known  as  the  Velvet  Ants  or  Stinging  Ants  (Mutillidse), 
many  of  the  insects  live  in  the  nests  of  wasps  and  bees  while  others  dig 
holes  in  the  ground  and  store  flies  and  other  small  insects  there,  it  has 
been  claimed.  The  males  (Fig.  373)  are  winged,  while  the  females  (Fig. 
374)  are  wingless  and  very  active.  Both  sexes  are  generally  densely 
covered  with  hairs,  often  long,  and  generally  of  two  or  three  contrasting 
colors,  such  as  black  with  a  red  cross-band,  or  white,  yellow  and  black. 
The  females  sting  very  effectively.  Northern  species  are  nearly  all  quite 


THE  HYMENOPTERA 


357 


small  but  in  the  South  are  forms  which  are  nearly  an  inch  long  and  stout- 
bodied. 

In  another  family  of  this  group  one  species  known  as  the  Tarantula- 
killer  (Fig.  375)  digs  nests  which  it  stores  with  tarantulas,  the  large  hairy 


FIG.  373.  FIG.  374. 

FIG.  373. — A  male  Mutillid  (Traumatomutilla  colorata  Gerst).  About  twice  natural 
size.  (After  Andre.) 

FIG.  374. — A  female  Mutillid  (Ephuta  occidentalis  L.),  slightly  enlarged.  (After 
Andre.) 

spiders  of  the  South  and  Southwest  where  this  insect  is  found.  It  is  a 
large  and  powerful  wasp,  about  two  inches  long,  but  in  its  battles  with 
the  tarantula  it  is  not  always  the  victor. 


FIG.  375. — Tarantula-killer    (Pepsis   marginata    Fab.),    somewhat    reduced.     (Original.) 

The  insects  of  the  family  Eumenidse  are  very  abundant  in  this 
country.  Most  of  them  are  rather  small  (Fig.  376),  and  black  with  yellow 
markings  seems  to  be  the  favorite  color  combination,  as  so  frequently  is 
the  case  with  the  other  groups  of  wasps.  Some  make  burrows  in  the 


358 


APPLIED  ENTOMOLOGY 


ground;  others  tunnel  in  wood  and  divide  the  tunnel  into  cells  by  cross 
partitions  of  mud;  while  others  build  cells  of  mud.  some  kinds  of  which, 
attached  to  twigs  are  like  jugs  or  urns  (Fig.  377)  in  form,  with  an  upper 
flaring  lip  which,  after  the  nest  has  been  stocked  with  food  for  their  young, 

is  sealed  with  mud.     The  mud  workers  of  this 

family  are  often  called  the   Mason-wasps.     All 
the  wasps  of  this  group  are  predaceous. 

In  the  family  Vespidse  we  come  to  the  social 
wasps,  living  in  colonies,  and  with  three  types  of 
members,  the  males,  females  and  workers,  these 


FIG.  376.  FIG.  377. 

FIG.  376. — Eumenid  Wasp  (Eumenes  fraternus  Say),  natural  size.      (Original.) 
FIG.  377. — Two  nests  ofEumenes  fraternus,  natural  size.     (Original.) 

last  being  females  in  which  the  reproductive  organs  have  undergone 
little  or  no  development  and  the  insects  themselves  are  smaller  than  the 
true  females. 

The  colonial  life  of  these  insects  continues  only  during  the  summer, 
all  but  the  females  dying  as  winter  approaches.     In  the  spring  the 


FIG.  378.  FIG.  379. 

FIG.  378. — Social  Wasp  (Polistes  pallipes  Lep.),  about  natural  size.      (Original.) 
FIG.  379. — Nest  of  Polistes  pallipes,  as  found  before  the  colony  has  increased  much 
in  numbers.     Reduced  slightly.      (Original.) 

female  (Fig.  378)  starts  a  colony,  first  building  a  cluster  of  six-sided  cells 
which  are  in  some  cases  attached  to  the  under  side  of  some  projecting 
rock,  eaves,  or  in  a  similar  position  (Polistes).  These  cells  (Fig.  379). are 
made  from  weathered  wood,  chewed  up  by  the  insect  into  a  sort  of  gray 


THE  HYMENOPTERA 


359 


paper  pulp  and  then  molded  into  the  desired  form.     In  these  cells  she 

now  places  eggs  and  the  young  which  hatch  are  fed  upon  insects  partly 

chewed  up,  with  perhaps  the  addition  of  some  pollen.     The  young  feed 

upon  this  until  full-grown,  then  pupate  in  their  cells.     The  adults  which 

emerge  are  workers  and  they  now  begin  to 

construct    additional   cells    all   in   the   same 

layer;  feed  the  young  and  do  the  other  work 

of  the  colony.    Later  in  the  season  males  and 

females  are  also  produced  and  mate.     Late 

fall  stops  further  growth  of  the  colony  and  all 

but  the  females  die. 

Other  insects  of  this  family  (Vespula,  Fig. 
380)  use  wood  partially  decayed,  with  which 
to  construct  their  nests,  and  an  outside  wrap- 
ping is  added.  Here  one  layer  of  cells  will  not  accommodate  the  colony 
and  several  layers  or  tiers  of  cells  surrounded  by  these  wrappings  are  pro- 
duced, leaving  only  one  or  two  exit  openings.  Sometimes  these  nests  are 
placed  in  holes  in  the  ground  and  the  wasps  locating  in  such  places  are 


FIG.  380.— Social  Wasp 


FIG.  381. — Nest  of  a  Hornet  (Vespula  maculata  Kirby.),  about  one-eighth  natural  size. 

(Original.) 

often  called  " yellow-jackets."  Other  species  construct  their  nests  in 
trees  or  bushes  (Fig.  381),  attaching  them  to  a  branch  or  branches. 
There  are  several  outside  wrappings  of  gray  papery  wood  pulp  surround- 
ing the  tiers  of  cells  within,  of  which  there  may  be  three  or  four,  and  the 
exit  opening  is  usually  at  or  near  the  bottom  of  the  nest.  Insects  making 
nests  of  this  kind  in  trees  or  under  eaves,  gable-ends  of  buildings  or 


360  APPLIED  ENTOMOLOGY 

similar  places,  are  generally  called  hornets,  though  there  is  really  no 
sharp  distinction  between  them  and  yellow-jackets,  in  the  usual  use  of 
these  names.  The  life  of  the  colony  in  the  case  of  these  insects  does  not 
differ  from  that  of  the  forms  described  above  which  make  only  one 
layer  of  cells  with  no  outside  wrappings  (Polistes),  but  in  the  yellow- 
jackets  and  hornets  the  colony  increases  much  more  rapidly  and  by  fall 
may  number  several  hundred  individuals. 

Taking  the  wasps  as  a  whole,  we  find  an  interesting  progressive 
development  in  the  different  groups.  As  regards  their  habitations,  we 
may  perhaps  regard  the  holes  dug  in  the  ground  as  being  the  simplest, 
followed  by  excavations  of  the  pith  of  woody  stems,  the  construction 
of  mud  nests  and  finally  along  this  line  the  formation  of  artistically 
shaped  urns,  as  progressive  steps  in  architectural  ability.  The  con- 
struction of  hexagonal  cells  of  paper  pulp,  first  in  a  single  layer,  then  in 
several  layers  surrounded  by  a  paper  wrapping  and  finally  much  more 
substantially  built  to  resist  exposure  to  the  weather  above  ground  may 
be  regarded  as  continued  progress  in  this  line;  the  nest  of  the  hornet 
marking  the  climax  of  the  series. 

Somewhat  parallel  to  this  is  the  nature  of  the  food.  The  nests 
in  the  ground,  in  plant  stems,  and  in  mud  cells,  are  provisioned  with 
insects  stored  as  food  for  the  young  of  the  forms  constructing  them: 
in  other  words  these  wasps  are  parasitic  insects.  With  the  appearance  of 
cells  of  paper  pulp  the  food  changes  to  a  mixture  of  insects  killed  and 
partly  chewed  up,  and  of  plant  materials  such  as  pollen.  At  this  same 
point  also,  a  change  from  a  solitary  to  a  colonial  life  begins  and  as  the 
colony  becomes  larger  the  nest  increases  in  size  and  strength. 

There  is  therefore  a  progressive  development  in  the  insects  of  these 
Superfamilies,  illustrated  in  nest  structure,  food,  and  the  advance  from 
solitary  life  to  that  of  a  large  colony. 

Superfamily  Apoidea  (The  Bees). — The  bees  familiar  to  everybody, 
are  the  bumblebees  and  the  honey  bee,  but  these  form  a  very  small  part 
of  the  insects  belonging  in  this  superfamily.  Many  of  the  bees  are 
solitary  in  their  habits;  are  rather  small  insects  and  little  attention 
is  paid  to  them.  They  are  important  insects,  however,  valuable  to  man 
as  they  visit  flowers  and  cross  pollinate  the  blossoms. 

The  bees  have  the  first  segment  of  the  hind  tarsus  somewhat  enlarged 
and  flattened,  and  in  those  which  carry  pollen  there,  hairs  are  present 
to  aid  in  this.  In  addition,  the  hairs  on  the  thorax  are  branched  or 
plumose  while  in  the  other  Hymenoptera  they  are  simple. 

Some  of  the  bees  are  solitary  (Fig.  382)  and  dig  holes  in  the  ground, 
generally  with  side  pockets  in  which  pollen  or  pollen  and  honey  are 


THE  UYMENOPTERA  361 

placed  as  food  for  the  young.  An  egg  is  then  laid  in  each  pocket. 
Others  lay  their  eggs  in  the  nests  of  other  bees  and  are  parasites  upon 
them,  or  inquilines  in  some  cases,  consuming  the  food  provided  for  the 
rightful  inhabitant  and  starving  it.  Some  construct  mud  nests  while 
others  cut  off  pieces  of  leaves  or  sometimes  flower  petals,  with  which 
they  line  cavities  they  excavate  in  wood,  for  their  nests,  and  still  others 
tunnel  in  wood  but  use  no  leafy  lining.  The  colonial  forms  establish 
their  homes  in  various  places  and  build  combs  of  wax  .in  which  to  store 
the  pollen  and  nectar  which  is  their  food  and  that  of  their  young. 

Though  many  of  the  bees  are  solitary  there  is  in  some  species  a 
tendency  to  make  their  holes  in  groups  forming  what  are  frequently 
called  "bee  villages/'  In  a  number  of  species  this  goes 
still  further,  several  bees  uniting  in  the  excavation  of 
a  central  burrow  but  each  making  lateral  passages 
from  this  to  cells  which  are  her  own  and  in  which  her 
own  young  are  produced.  If  the  former  could  fairly  be 
called  "villages"  it  would  seem  that  these  last  could 


with    equal    propriety   be    described     as    "apartment       FIG.  382.—  Soli- 


houses,"  as  has  been  done.     Some  of  the   bee   villages    ^ry   Bee-  some- 
will  include  several  thousand  nests  within  a  few  square    (Original.) 
feet  and  might  even  be  termed  "bee  cities." 

Some  bees  have  a  rather  short  hinder  lip  and  are  known  as  the  "short- 
tongued  bees,"  but  in  the  majority  of  these  insects  the  central  portion  is 
long  and  slender,  enabling  such  forms  to  reach  the  nectar  in  long-tubed 
flowers  that  would  otherwise  be  inaccessible  to  them. 

.The  leaf-cutter  bees  are  usually  rather  small.  Their  nests  are  not 
often  noticed,  being  made  in  holes  (frequently  in  wood)  sometimes 
dug  by  the  bees  themselves,  but  the  leaves  which  they  cut  are  familiar 
objects  as  the  cut  is  frequently  a  very  true  circle  or  double  circle,  the 
piece  removed  in  the  latter  case  being  rather  oblong  with  rounded  ends. 

The  large  Carpenter  Bees  (Xylocopa)  are  about  the  size  of  bumble 
bees  but  in  most  cases  are  easily  distinguished  from  them  by  the  smooth 
and  glossy  upper  surface  of  the  abdomen.  These  insects  tunnel  in 
wood,  often  to  quite  a  distance.  The  tunnels  are  divided  into  cells  by 
partitions  of  wood  chips,  a  partition  being  built  across  after  each  cell 
has  been  provided  with  a  mixture  of  pollen  and  nectar  and  an  egg. 

Bumblebees  (Bombus,  etc.,  of  many  species).  —  There  are  many  kinds 
of  bumblebees  widely  distributed  over  the  globe  but  none  are  found  native 
in  Australia.  They  live  in  colonies  during  the  summer  but  only  the  queens 
(females)  survive  the  winter.  In  spring  the  queen  (Fig.  383)  seeks  some 
suitable  place  for  a  nest,  generally  a  hole  in  the  ground,  and  frequently 
the  deserted  nest  of  a  field  mouse  is  chosen  for  the  purpose.  Here  she 
places  a  mass  of  pollen  on  which  she  lays  some  eggs,  and  the  larvae  which 
hatch,  feed  upon  the  pollen,  and  when  full-grown  pupate  in  silken  cocoons 


362  APPLIED  ENTOMOLOGY 

from  which  workers  emerge.  These  are  undeveloped  females, '  smaller 
than  the  queen,  and  they  now  take  up  the  work  of  the  colony,  strengthen- 
ing the  cocoons  with  wax  and  using  them  to  store  honey  in.  The  colony 
increases  in  numbers  and  late  in  the  season  males  (drones)  and  females 
(queens)  are  also  produced  and  live  together  until  the  approach  of  cold 
weather,  when  all  but  the  young  queens  die,  these  going  to  protected  places 
to  pass  the  winter. 

The  value  of  the  bumblebees  to  man  is  apparently  based  upon  the 
fact  that  in  these  insects  the  middle  part  of  the  hinder  lip  (tongue) 
is  longer  than  in  most  of  the  other  bees,  and  that  therefore  they  visit  and 

cross  pollenize  flowers  having  a 
nectary  so  long  that  the  nectar  in  it, 
from  which  honey  is  made,  cannot 
be  reached  by  the  other  species, 
which  accordingly  do  not  visit  such 
flowers.  One  such  plant  is  the  com- 
mon red  clover  which  in  the  United 
States  is  enabled  to  produce  seed, 
chiefly  as  a  result  of  the  visits  of 


FIG.  383.—  Queen    Bumblebee   (Bom-    bumblebees,      which     makes     these 
*  insects  important  aids  to  those  who 


raise  clover  seed. 

Insects  so  closely  resembling  bumblebees  that  it  has  incorrectly 
been  said  that  the  latter  cannot  distinguish  them  from  themselves,  are 
often  found  in  bumble  bee  nests,  living  there  as  inquilines.  The  females 
of  these  inquilines  (genus  Psiihyrus)  however,  have  no  structures  on 
their  hind  tarsi  for  carrying  pollen.  In  these  inquilines  there  is  no  worker 
caste.  The  eggs  are  laid  in  the  bumblebee  cells  and  on  hatching  the 
young  are  fed  by  the  bumblebee  workers  like  their  own,  and  the  adults 
go  in  and  out  of  the  nest  without  molestation.  Whether  they  have  some 
function  beneficial  to  the  insects  with  which  they  live  and  which  provide 
for  them  is  as  yet  unknown. 

The  Honey  Bee-  (Apis  melliferalj.  ).  —  There  are  a  number  of  species 
of  honey  bees  in  different  parts  of  the  world,  but  in  the  United  States 
our  knowledge  and  experience  with  these  insects  is  limited  to  the  above 
named  kind,  often  called  also,  the  Hive  Bee. 

This  insect  is  a  native  of  Europe  but  was  introduced  into  America 
centuries  ago.  In  many  instances,  colonies  have  escaped  from  domesti- 
cation and  wild  honey  bees  are  abundant  as  a  result.  There  are  several 
races  of  the  Honey  Bee,  the  most  common  one,  at  least  wild,  being  the 
Black  or  German  bee,  as  this  was  the  first  race  to  be  brought  to  this 
country.  The  German  bee  has  a  black  abdomen;  is  not  a  particularly 
good  honey  producer  and  has  a  decidedly  bad  temper,  besitdes  being  less 
able  to  protect  itself  from  some  of  the  insects  such  as  the  bee  moth,  which 


THE  HYMENOPTERA 


363 


live  in  its  nests,  than  are  some  of  the  other  races.  The  Italian  bee  is  a  slightly 
larger  insect  with  dull  yellow  stripes  on  its  abdomen;  an  excellent  honey 
producer,  gentle  in  disposition;  can  protect  itself  quite  well  from  other 
insects,  and  at  the  present  time  is  the  most  popular  race  in  this  country. 
Other  races  more  or  less  frequently  met  with  are  the  Carniolan  having  a 
gray  abdomen,  the  Cyprian  with  a  yellow  abdomen  and  a  very  bad  tem- 
per, and  the  Caucasian  with  a  yellow-gray  abdomen.  Interbreeds  of  the 
black  and  Italian  bees  are  very  common  and  have  more  black  on  the 
abdomen  than  the  pure-bred  Italians. 


/ 


FIG.  384.— Honey  Bee  (Apis  mellifera  L.):  a,  drone;  b,  queen;  c,  worker. 

size.      (Original.) 


About  natural 


A  honey  bee  colony  consists  of  a  queen  or  fully  developed  female; 
workers  which  are  partly  developed  females;  and  drones  or  males  during 
a  part  of  the  year  .(Fig.  38.4).  The  queen  lays  eggs  in  the  cells  and  the 
young  are  cared  for  by  the  workers  which  also  gather  food  for  themselves 
and  the  3^oung  bees,  make  the  comb,  put  the  nest  in  good  condition  and 
keep  it  so,  and  in  fact  do  all  the  work  necessary  for  the  colony.  The 
drones  exist  solely  to  fertilize  the  queens,  taking  no  part  in  the  work  of  the 
colony,  and  feeding  on  the  stores  brought  in.  On  the  first  tarsal  segment 
of  the  hind  leg  in  the  workers  is  the  "  pollen  basket,"  a  flattened  or  slightly 
hollowed  oval  surface  surrounded  by  a  fringe  of  long  hairs. 

An  ordinary  colony  in  good  condition  will  consist  of  several  thousand 
bees,  the  number  at  any  time  varying  and  determined  by  the  rapidity  of 
the  production  of  young,  the  departure  of  many  by  swarming,  and  other 
factors.  Swarms  containing  over  fifty  thousand  bees  have  been  seen, 
and  the  colony  they  left  behind  also  contained  at  least  a  few  thousand. 

A  laying  queen  bee  has  a  body  about  three  quarters  of  an  inch  long: 
the  drone  has  a  shorter  but  stouter  abdomen,  and  the  workers  are  about 
half  an  inch  long. 

The  life  of  the  queen  may  be  several  years.  Ordinarily,  workers  live 
only  a  month  or  two,  but  those  produced  in  the  fall  live  over  winter  and 
far  enough  into  the  spring  to  care  for  the  young  produced  at  that  time. 
Drones  live  only  a  few  months  and  are  killed  by  the  workers  when  their 
usefulness  is  ended. 

The  life  of  the  honey  bee  has  been  modified  in  many  ways  by  its 
relation  to  man.  Under  natural  conditions  where  no  human  interference 


364  APPLIED  ENTOMOLOGY 

occurs,  the  following  may  be  regarded  as  an  outline  of  the  life  of  a  bee 
colony. 

Starting  with  a  "swarm/'  which  consists  of  a  laying  queen  a.nd  a 
mass  of  workers,  which  has  left  its  former  home,  this  swarm  flies  to  a  new 
place  in  which  to  establish  itself,  such  as  a  hollow  tree.  Here  the  workers 
clean  out  the  cavity,  removing  loose  particles  of  wood  and  such  other 
debris  as  can  be  carried  out.  All  cracks  and  openings  to  the  exterior 
except  one  or  two,  are  then  stopped  up  with  Propolis,  a  dark-colored, 
sticky  material  which  the  bees  gather  from  the  buds  of  trees,  particularly 
poplars  where  these  trees  occur,  and  carry  to  the  nest  in  their  pollen 
baskets. 

The  production  of  wax  with  which  to  make  cells  in  which  food  is 
stored  and  the  brood  raised,  is  next  in  order.  To  obtain  this,  some  of 
the  workers  feed  freely  and  hang  upon  the  walls  of  the  nest  but  do  no 
work.  Soon  tiny  scales  of  wax  appear  on  the  under  side  of  the  abdomens 
of  these  workers,  produced  by  wax  glands  along  the  inner  side  of  the  chi- 
tinous  wall  of  the  body  there,  and  poured  out  through  openings  leading 
from  these  glands  to  the  surface.  This  wax  is  gathered,  worked  over  and 
molded  into  the  form  of  sheets  of  "comb,"  attached  at  their  tops  to 
some  part  of  the  hive  and  hanging  downward.  Generally  these  sheets 
are  more  or  less  parallel  to  each  other  and  with  only  a  narrow  space  left 
between  them  when  their  construction  has  been  completed. 

Each  sheet  of  comb  consists  of  two  layers  of  cells  back  to  back,  each 
cell  being  six-sided.  The  long  axis  of  the  cell  is  nearly  at  right  angles  to 
the  plane  of  the  sheet  of  comb  as  a  whole,  but  tipped  slightly  upward. 
Comparing  cells  on  the  two  sides  of  the  comb  it  is  seen  that  a  cell  of  one 
side  backs  against  parts  of  three  of  the  opposite  side,  and  that  the  parti- 
tion at  the  inner  end  of  each  cell  slopes  so  that  the  center  is  its  deepest 
point.  Mathematical  study  of  the  construction  of  the  cells  shows  that 
by  this  form  and  arrangement  of  the  cells  the  greatest  amount  of  storage 
space  is  obtained  with  the  least  expenditure  of  wax,  of  any  form  which  the 
bees  could  use.  In  some  of  these  cells,  usually  those  around  the  top  and 
sides  of  the  comb,  food  is  stored,  while  the  central  and  lower  portions 
are  used  for  the  production  of  the  young. 

As  soon  as  comb  is  available  the  storing  of  food  and  the  production  of 
young  begin.  The  workers  go  out  and  visit  flowers,  gathering  the  pollen 
in  their  pollen  baskets  and  bringing  it  to  the  nest  where  it  is  stored  in 
cells.  They  also  collect  nectar  from  the  blossoms,  carrying  it  to  the  nest 
in  the  honey  sac,  an  enlargement  of  the  oesophagus  just  in  front  of  the 
stomach  (Fig  24,  hs) .  On  reaching  the  nest  this  nectar  is  expelled  into  a 
cell  and  the  cells  selected  for  this  purpose  are  gradually  filled.  From  time 
to  time  workers  visit  these  cells  and  draw  the  nectar  from  them  into  their 
honey  sacs,  then  driving  it  back  into  the  cell  again  and  repeating  the 
process,  which  removes  water  from  it  and  concentrates  it  into  honey. 


THE  HYMENOPTERA  365 

The  queen  lays  her  eggs  on  the  bottoms  of  the  cells  selected  for  the 
raising  of  brood,  one  egg  in  the  bottom  of  each  cell.  The  eggs  hatch  into 
stout,  white,  maggot-like  larvae  (Fig.  385)  which  are  fed  by  the  worker 
bees  with  a  material  generally  called  "bee  bread"  which  appears  to  be 
pollen  mixed  with  some  honey.  When  the  larvae  are  full-grown  and  ready 
to  pupate  the  workers  cap  over  with  wax  the  openings  of  the  cells  occu- 
pied by  such  larvae  and  these  proceed  to  pupate  (Fig.  385).  After  the 
changes  undergone  during  pupation  have  been  completed  the  adult  thus 
produced  bites  away  the  cap  closing  the  cell  it  is  in  and  emerges  as  the 
adult. 


CO 


FIG.  385. — Section  of  comb  of  Honey  Bee:  FL,  feeding  larva  in  the  bottom  of  its  cell; 
SL,  larva  ready  to  pupate,  spinning  its  cocoon;  N,  pupa;  an,  antenna;  ce,  compound  eye; 
co,  cocoon;  e,  excrement;  ex,  exuvium;  m,  mandible;  sp,  spiracle;  t,  tongue;  w,  wing.  (After 
Cheshire.) 

In  the  case  of  eggs  which  are  to  become  drones  (males)  the  cells  in 
which  such  eggs  are  laid  are  apparently  of  a  slightly  greater  diameter  than 
those  where  workers  are  to  be  produced,  though  this  is  denied  by  some 
students  of  the  subject,  and  they  are  longer,  projecting  out  beyond  the 
line  of  the  general  surface  of  the  brood  cells,  at  least  after  being  capped,  so 
that  they  are  easily  recognized. 

The  queen  is  fertilized  but  once,  at  which  time  the  sperms  of  the  drone 
are  stored  in  the  seminal  receptacle  of  the  queen.  She  lays  both  fertilized 
and  unfertilized  eggs,  the  latter  producing  the  drones.  By  the  Dzierzon 
theory,  whether  the  egg  is  to  be  fertilized  or  not  depends  upon  the  will  of 
the  queen.  If  the  cell  in  which  the  egg  is  to  be  laid  is  a  worker  cell,  at  the 
moment  the  egg  passes  down  the  oviduct  by  the  opening  of  the  seminal 
receptacle  the  muscles  surrounding  the  receptacle  are  slightly  contracted 
and  sperms  are  expelled,  one  of  which  fertilizes  the  egg,  while  if  the  egg 
is  deposited  in  a  drone  cell  the  muscles  are  not  contracted  and  the  egg  is 
unfertilized  and  produces  a  drone.  While  this  is  the  more  generally 
accepted  theory,  the  alternative  view  is  held  by  some  persons  that  the 
smaller  diameter  of  the  worker  cell  produces  pressure  on  the  abdomen 
of  the  queen  which  forces  some  of  the  sperms  out,  and  that  in  case  of 
drone  cells  their  greater  diameter  prevents  this. 

Queens  are  produced  only  during  the  late  spring  and  summer  months 
when  swarming  is  desired.  At  such  times  the  workers  select  a  cell  already 


366  APPLIED  ENTOMOLOGY 

containing  a  worker  egg  and  tear  down  those  around  it  and  construct  a  new 
cell  about  the  shape  and  size  of  a  small  peanut,  to  enclose  the  egg,  and  with 
its  opening  usually  facing  downward.  When  the  egg  in  this  cell  hatches 
the  larva  is  fed  on  " royal  jelly"  which  is  probably  bee  bread  mixed  with 
an  albuminous  secretion  derived  from  glands  situated  in  the  heads  of  the 
workers,  and  which  is  richer  and  more  nutritious  than  bee  bread.  With 
this  richer  food  and  a  larger  space  in  which  to  develop,  the  workers  are 
thus  able  to  produce  a  queen  from  a  worker  egg.  There  are  often  a  num- 
ber of  queen  cells  of  different  ages  in  a  nest  at  once. 

The  time  required  to  produce  a  queen  from  egg  to  adult  is  about  15J^ 
days:  for  a  worker,  21  days;  and  for  a  drone  24  days. 

Swarming  is  for  the  double  purpose  of  relieving  colonies  whose  nests 
would  otherwise  become  over-crowded,  and  for  the  establishment  of 
new  ones.  Though  many  of  the  details  of  this  process  may  vary  on 
different  occasions,  the  usual  story  of  swarming  is  about  as  follows. 

When  the  colony  is  in  such  a  condition  during  late  spring  or  summer 
that  swarming  will  soon  be  desirable,  drone  cells  and  queen  cells  are  con- 
structed and  after  a  time  the  first  of  the  new  queens  completes  pupation 
and  begins  to  bite  off  the  wax  cap  over  the  mouth  of  her  cell.  At  this 
time  she  makes  a  peculiar  noise  commonly  called  a  "piping"  sound,  and 
when  the  old  queen  hears  this  she  becomes  greatly  disturbed  and  begins 
to  hunt  for  the  young  queen  to  sting  and  kill  her  before  she  can  escape 
from  her  cell,  if  possible.  If  a  swarm  just  at  that  time  is  not  desired  by 
the  workers  for  any  reason,  she  may  be  allowed  to  do  this,  but  if  swarm- 
ing is  to  take  place  workers  cluster  so  thickly  over  and  around  the  young 
queen  cell  that  the  old  queen  cannot  reach  it.  This  opposition  to  her 
wishes,  passive  though  it  is,  or  the  knowledge  that  another  queen  will 
quickly  be  present  in  the  colony  seems  to  arouse  and  excite  the  old  queen 
greatly  and  this  excitement  spreads  to  the  workers,  particularly  the 
younger  ones.  Scouts  now  go  out  to  find  a  home  for  the  swarm  and 
finally  the  old  queen  and  a  mass  of  workers  leave  the  hive  together.  In 
some  cases  they  go  directly  to  their  new  home,  but  most  often  they  fly 
only  a  short  .distance  before  clustering  on  the  limb  of  some  bush  or  tree 
for  a  time  before  flying  to  the  new  nest.  Once  arrived  there,  the  work  of 
preparing  the  place,  stopping  the  cracks  and  the  production  of  comb 
begins,  as  already  described. 

That  part  of  the  colony  remaining  behind  now  consists  of  workers, 
drones  and  a  young,  unfertilized  queen.  The  queen  on  escaping  from 
her  cell  usually  explores  the  brood  cells  and  if  she  finds  other  queens 
developing  she  stings  them  in  their  cells  to  assure  her  supremacy,  unless 
prevented  by  the  workers.  A  few  days  later  the  queen  leaves  the  nest  on 
a  pleasant  day  for  a  flight  during  which  she  mates,  after  which  she  returns 
to  take  up  her  duties  as  queen  of  the  colony. 

Several  possibilities  may  become  realities  in  connection  with  swarm- 


THE  HYMENOPTERA  367 

ing.  One  of  these  is  the  chance  that  two  young  queens  may  emerge 
at  almost  the  same  time.  If  this  should  happen  it  is  stated  that  the 
two  meet  sooner  or  later  and  struggle  for  supremacy  until  one  or  the 
other  is  killed.  A  second  possibility  is  that  both  of  the  queens  may 
be  so  injured  that  they  will  die,  or  as  probably  is  more  often  the  case, 
the  queen  while  out  on  her  mating  flight  may  be  killed  by  a  bird  or  in 
some  other  way.  In  either  case  the  colony  becomes  queenless  as  a  result. 
If  other  queen  cells  are  present  in  such  cases,  the  workers  carry  on  the 
-work  of  the  hive  until  the  new  queen  appears,  mates  and  takes  charge: 
but  if  there  are  no  more  queen  cells  the  workers  look  about  for  a  worker 
egg  or  a  larva  not  more  than  3  days  old.  If  one  is  found,  its  cell  walls 
are  torn  down  and  a  queen  cell  built  around  it  and  its  food  is  changed 
from  bee  bread  to  royal  jelly  and  in  this  way  a  queen  will  be  produced. 
If  an  egg  or  a  worker  larva  under  this  age  cannot  be  found,  however,  the 
colony  cannot  hope  to  obtain  a  queen  and  it  gradually  dwindles  away  and 
is  lost. 

Drones,  serviceable  to  the  colony  during  the  swarming  season,  are 
not  needed  thereafter  and  would  consume  stores  gathered  for  winter. 
Therefore  after  all  swarming  is  over  they  are  dragged  out  and  killed 
by  the  workers. 

The  value  of  the  honey  bee  to  man  comes  from  the  honey  and  wax 
it  produces.  The  amount  obtained  varies  greatly  from  year  to  year 
but  averages  over  fifty  million  pounds  a  season  in  the  United  States 
and  at  a  recent  average  retail  price  of  forty  cents,  would  represent  about 
twenty  million  dollars.  This  is  probably  more  though,  than  is  actually 
received  by  the  beekeepers.  About  a  million  pounds  of  wax  are  now 
produced  annually  and  at  about  forty  cents  per  pound  this  would  add 
nearly  half  a  million  dollars  more  to  the  value  of  the  industry  in  this 
country. 

Superfamily  Formicoidea  (The  Ants). — These  familiar  and  plentiful 
insects  occur  from  the  frigid  regions  to  the  equator,  being  present  in 
abundance  practically  everywhere,  and  it  has  been  claimed  that  there 
are  more  individuals  of  ants  than  of  all  other  terrestrial  animals.  They 
live  in  colonies  which  are  quite  permanent,  enduring  for  many  years  in 
some  cases,  and  the  life  of  an  individual  ant  may  continue  for  several 
years. 

Ants  are  nearly  always  easily  recognized  by  the  presence  of  a  petiole 
which  is  enlarged  near  or  behind  its  middle  (Fig.  386e),  being  either 
swollen  or  having  a  portion  projecting  upward  there,  followed  behind 
by  a  constriction  where  this  segment  joins  the  rest  of  the  abdomen. 
In  some  ants  the  following  segment  is  also  more  or  less  similarly  shaped. 
This  gives  these  insects  a  rather  elongate,  narrow  portion  between  the 
thoracic  and  abdominal  masses,  enlarged  at  one  or  two  places,  according 
to  the  number  of  segments  concerned. 


368 


APPLIED  ENTOMOLOGY 


Three  classes  of  ants  always  compose  a  colony — males,  queens 
(females)  and  workers — and  there  may  be  subdivisions  of  each  of  these 
in  some  cases.  The  males  and  females  usually  have  wings  during  a 
portion  of  their  lives,  these  having  a  simple  arrangement  of  the  veins: 
the  workers  are  wingless  though  some  have  vestiges  of  these  structures. 
The  queens  and  workers  are  provided  with  a  well-developed  sting  in  some 
groups  of  ants,  while  in  others  it  is  vestigial  or  entirely  absent.  The 
usual  colors  of  ants  are  yellow,  brown,  black,  red,  dull  red,  or  brownish 
yellow. 


FIG.  386. — Little  Black  Ant  (Monomorium  minimum  Em.) :  a,  male;  b,  pupa;  c,  female; 
d,  winged  female;  e,  worker;  /,  larva;  g,  eggs;  workers  in  line  of  march  below.  All  enlarged, 
hair  lines  showing  true  length.  (From  U.  S.  D.  A.  Farm.  Bull.  740.) 

Colonies  of  ants  occur  in  many  kinds  of  locations.  Some  are  in 
the  ground  and  these  may  be  of  different  types  of  structure;  some  occur 
in  the  cavities  of  plants,  either  preformed  or  else  tunneled  out  by  the  ants: 
some  form  nests  on  branches,  making  them  of  various  materials;  and 
some  nest  in  timbers,  or  other  unusual  places,  while  a  few  kinds  have  no 
fixed  homes. 

The  food  of  ants  is  as  varied  as  are  their  nest  locations.  Probably 
the  original  food  of  the  group  was  insects,  either  dead  or  helpless,  and 
many  species  feed  on  this  material.  Others  take  the  honey-dew  supplied 
by  scale  insects,  leafhoppers  and  particularly  by  plant-lice.  Some  raid 


THE  HYMENOPTERA  369 

the  nests  of  other  species  of  ants  and  feed  on  their  larvae  and  pupae. 
Plant  seeds,  bulbs,  and  the  bark  on  tender  roots  also  form  the  food  of 
some  ants,  and  one  tribe  raises  a  fungus  in  order  to  feed  upon  its  hyphae. 
Sweet  materials  such  as  cake,  candy,  sugar,  molasses,  etc.,  in  houses, 
often  attract  ants,  which  find  in  these  substances  satisfactory  foods. 

Colonies  in  the  ground  may  vary  from  those  having  a  single  tiny 
entrance  and  a  few  tunnels  and  galleries  below  the  surface,  to  large 
ant  hills  several  yards  in  diameter  and  several  feet  high,  with  extensive 
galleries  both  above  and  below  the  general  ground  level(  Fig.  388).  In 
these  nests  may  be  found  a  queen  (frequently  several) ;  males,  at  least  at 
times;  and  often  many  thousands  of  workers.  The  queen  or  queens 
produce  the  eggs  which  are  carried  away  and  cared  for  by  the  workers, 
who  also  feed  the  larvae,  clean  them,  transfer  them  from  one  part  of 
the  nest  to  another,  according  to  the  temperature  and  other  conditions 
they  need,  and  finally  aid  them  in  escaping  from  their  cocoons.  They 
also  feed  the  queen  and  do  all  the  work  of  the  colony. 

The  eggs  laid  may  develop  either  into  males  or  females  and  workers, 
and  Dzierzon's  theory  given  above  for  bees  has  been  applied  to  ants  also, 
though  some  evidence  that  unfertilized  eggs  may  in  certain  cases  produce 
workers  tends  to  throw  doubt  on  the  applicability  of  this  theory  to  ants. 

At  certain  seasons  of  the  year  swarming  occurs.  At  such  a  time 
enormous  numbers  of  winged  males  and  females,  previously  produced  in 
the  nest,  leave  it  and  take  flight.  Mating  occurs  in  the  air  and  the 
females  soon  return  to  the  ground  where  they  remove  their  now  useless 
wings,  either  by  pulling  them  off  with  their  legs  or  jaws,  or  by  rubbing 
them  against  the  ground,  stones  or  grass-stems.  The  queen  now  prepares 
a  nest  by  digging  a  hole  in  the  ground,  in  rotten  wood  or  elsewhere, 
forming  a  small  chamber  at  the  inner  end  and  closing  the  entrance. 

"In  her  cloistered  seclusion  the  queen  now  passes  days,  weeks,  or  even 
months,  waiting  for  the  eggs  to  mature  in  her  ovaries.  When  these  eggs  have 
reached  their  full  volume  at  the  expense  of  her  fat-body  and  degenerating  wing- 
muscles,  they  are  laid,  after  having  been  fertilized  with  a  few  of  the  many  thou- 
sand spermatozoa  stored  up  in  the  spermatheca  during  the  nuptial  flight.  The 
queen  nurses  them  in  a  little  packet  till  they  hatch  as  minute  larvae.  These  she 
feeds  with  a  salivary  secretion  derived  by  metabolism  from  the  same  source  as 
the  eggs,  namely,  from  her  fat-body  and  wing-muscles.  The  larvae  grow  slowly, 
pupate  prematurely  and  hatch  as  unusually  small  but  otherwise  normal  workers. 
In  some  species  it  takes  fully  10  months  to  bring  such  a  brood  of  minim  workers 
to  maturity,  and  during  all  this  time  the  queen  takes  no  nourishment,  but 
merely  draws  on  her  reserve  tissues.  As  soon  as  the  workers  mature,  they  break 
through  the  soil  and  thereby  make  an  entrance  to  the  nest  and  establish  a  com- 
munication with  the  outside  world.  They  enlarge  the  original  chamber  and  con- 
tinue the  excavation  in  the  form  of  galleries.  They  go  forth  in  search  of  food 
and  share  it  with  their  exhausted  mother,  who  now  exhibits  a  further  and  final 
change  in  her  behavior.  She  becomes  so  exceedingly  timid  and  sensitive  to 

24 


370  APPLIED  ENTOMOLOGY 

light  that  she  hastens  to  conceal  herself  on  the  slightest  disturbance  to  the  nest. 
She  soon  becomes  utterly  indifferent  to  her  progeny,  leaving  them  entirely  to 
the  care  of  the  workers,  while  she  limits  her  activities  to  laying  eggs  and  imbibing 
liquid  food  from  the  tongues  of  her  attendants.  This  copious  nourishment 
restores  her  depleted  fat-body,  but  her  disappearing  wing-muscles  have  left  her 
thoracic  cavity  hollow  and  filled  with  air  which  causes  her  to  float  when  placed 
in  water.  With  this  circumscribed  activity,  she  lives  on,  sometimes  to  an  age  of 
15  years,  as  a  mere  egg-laying  machine"  (Wheeler). 

Of  course  there  are  many  fatalities  in  such  a  history  as  this.  Birds, 
dryness  in  their  burrows,  excessive  moisture  or  cold,  underground  insects 
attacking  them,  together  destroy  the  great  majority  of  these  ants  just 
starting  new  colonies.  Then  too,  the  amount  of  nourishment  stored  in 
the  individual  is  an  important  factor,  some  species  having  so  little  that 
they  are  wholly  unable  to  start  new  colonies.  An  individual  of  such  a 
species  therefore  either  joins  a  colony  already  established,  a  queenless 
colony  of  a  related  species  if  she  can  induce  the  colony  to  accept  her,  or 
she  may  enter  a  colony  of  a  very  different  species  and,  killing  its  members, 
raise  their  young  until  they  emerge  when  they  will  accept  her  as  their 
queen.  Rarely  two  queens  may  start  a  colony  together. 

After  the  colony  is  well  under  way  the  queen  limits  her  duties  to  egg 
laying,  and  may  live  many  years.  In  one  case  a  queen  lived  nearly 
15  years  in  confinement  and  may  have  been  older!  This  is  the  greatest 
age  known  to  have  been  attained  by  any  adult  insect.  The  males  die 
soon  after  mating. 

The  relation  of  ants  to  plant  lice  is  most  interesting  and  has  already 
been  referred  to  (pp.  197  and  203).  It  does  not  exist  with  all  species 
of  ants  but  in  at  least  a  large  number  honey-dew  is  an  important  part 
of  their  diet  and  in  some  cases  it  may  be  their  only  food.  There  is  every 
evidence  that  the  benefit  is  mutual,  the  ants  protecting  the  aphids,  driv- 
ing away  the  enemies  of  these  insects  or  carrying  the  aphids  to  protected 
places.  Ants  that  care  for  root-feeding  aphids  keep  them  in  chambers  or 
galleries,  conduct  them  to  their  sources  of  food  supply,  collect  and  store 
their  eggs  for  the  winter,  and  in  spring  take  the  young  to  their  food. 

The  Corn-root  Aphis  so  injurious  to  corn,  as  already  described,  is 
thus  cared  for  by  ants.  Scale  insects  which  produce  honey-dew  are  also 
cared  for  in  a  sense,  for  ants  are  very  attentive  to  them  and  to  quite  an 
extent  prevent  the  attacks  of  the  enemies  of  the  scales  by  their  presence 
and  activities.  Thus  in  an  indirect  way  the  protection  by  ants  of 
plant  lice,  scale  insects,  white  flies,  leaf  hoppers,  and  in  fact  any  insects 
which  produce  honey-dew,  establishes  such  ants  as  injurious. 

Some  kinds  of  ants  have  most  remarkable  habits  worthy  of  a  brief 
reference  here.  Some  species  may  make  raids  on  the  nests  of  other 
kinds,  and  carry  off  their  worker  larvae  and  pupae  to  their  own  nests, 
where  many  probably  serve  as  food  but  a  few  may  be  reared  and  become, 


THE  HYMENOPTERA  371 

slaves.  Sla,very  is  not  Essential  with  all  the  kinds  of  ants  where  it  is 
known,  colonies  having  no  slaves  being  able  to  carry  on  their  lives  unaided 
by  slaves.  With  certain  species,  however,  the  situation  is  different. 
In  these  the  workers  have  mandibles  so  constructed  that  they  are  unable 
to  gather  food,  excavate  their  nests  or  care  for  the  young.  Accordingly 
they  make  forays  on  the  nests  of  other  species,  bringing  back  larvae  and 
pupae  which  on  becoming  adult  are  slaves  which  do  the  work  of  the  colony 
and  care  for  their  captors,  both  as  adults  and  during  their  early  stages. 

The  honey  ants,  so-called,  include  those  species  in  which  the  crop  is 
capable  of  great  distention,  and  this  power  is  made  use  of  by  collecting 
honey-dew  and  storing  it  until  the  abdominal  mass  is  enormously  dis- 
tended and  (in  some  species)  about  the  size  of  a  large  currant,  such  in- 
dividuals becoming  animated  food  reservoirs.  These  members  of  the 
colony  hang  on  the  ceilings  of  their  galleries,  withdrawing  from  the 
regular  duties  of  the  other  workers.  The  reason  for  the  existence  of 
such  a  peculiar  habit  is  suggested  by  the  fact  that  the  honey  ants  are 
confined  to  dry  plains  and  desert  regions,  being  found  in  North  America, 
South  Africa  and  Australia.  They  are  therefore  probably  true  reservoirs 
of  nourishment  which  may  be  drawn  upon  during  periods  of  drought, 
when  the  ants  must  remain  for  some  considerable  time  in  their  nests. 

Some  ants  raise  fungi  upon  which  to  feed,  about  one  hundred  kinds 
which  do  this  being  known.  These  insects  in  most  cases  go  in  large  num- 
bers to  trees  and  some  climb  the  trees  and  cut  off  the  leaves  while  other 
members  of  the  colony  pick  these  up  from  the  ground  where  they  have 
fallen  and  carry  them  to  their  nests  where  the  fungus  is  grown  on  them. 

A  few  species  of  ants  are  obnoxious  to  man,  either  by  invading  houses, 
making  their  nests  in  lawns  or  in  trees,  or  by  to  some  extent  protecting 
injurious  insects. 

The  Argentine  Ant  (Iridomyrmex  humilis  Mayr.)  is  a  native  of 
South  America  which  probably  reached  this  country  between  1880  and 
1890  at  New  Orleans  and  now  is  present  nearly  everywhere  in  most  of  the 
southern  tier  of  states,  and  in  California  as  far  north  as  San  Francisco. 

The  adults  (Fig.  387)  are  brown  in  color.  The  queens  are  about  a 
quarter  of  an  inch  long,  the  males  about  half  that  length,  and  the  workers 
about  a  tenth  of  an  inch  long.  Their  summer  nests  "may  be  located 
anywhere — under  sidewalks,  under  the  sills  of  houses,  in  brick  piles,  stone 
piles,  under  a  piece  of  board  or  a  piece  of  tin,  in  an  old  tin  can — in  fact, 
in  any  place  convenient  to  the  food  supply.  In  the  winter  months  there 
is  a  tendency  to  concentrate  into  larger  colonies,  and  they  seek  warm, 
dry,  secure  nesting  places  in  which  to  hibernate"  (E.  R.  Barber). 

Egg  production  is  probably  quite  large — perhaps  50  or  more  per  day 
under  favorable  conditions — and  an  average  of  40  days  in  warm  weather 
is  required  for  development  from  the  laying  of  an  egg  to  the  emergence 
of  the  adult  worker. 


372 


APPLIED  ENTOMOLOGY 


This  is  one  of  the  worst  of  house  pests  known  in  the  regions  where  it  is 
abundant.  Its  small  size  enables  it  to  enter  through  the  smallest  cracks 
and  it  goes  everywhere  in  houses  after  its  food.  It  will  eat  practically 
everything  in  the  way  of  foods,  both  raw  and  cooked,  and  no  part  of  a 
house  is  free  from  its  presence.  The  cold  of  ice  chests  does  not  repel 
them  and  beds  are  not  entirely  protected  by  placing  the  bedposts  in  dishes 


FIG.  387. — Argentina  Ant  (Iridomyrmsx  humilis  Mayr.) :  1,  wingless  female;  2,  worker, 
3,  early  stages:  a,  eggs;  b,  young  larva;  c,  full-grown  larva;  d,  side  view  of  pupa;  e,  ventral 
side  of  pupa;  /,  dorsal  view  of  pupa,  4,  male.  All  greatly  enlarged.  (From  U.  S.  D.  A, 
Farm.  Bull.  740.) 

of  water  or  kerosene,  as  after  a  few  hours  a  film  of  dust  forms  on  the 
surface  of  this,  over  which  with  their  light  bodies  they  are  sometimes  able 
to  pass.  Though  they  do  not  sting,  they  bite  freely  and  are  able  to 
cause  some  pain  in  this  way.  Young  children  asleep  have  been  found 
with  ants  in  the  nose,  ears  and  mouth,  and  older  persons  are  frequently 
inconvenienced  by  them  in  a  similar  way.  They  visit  plant  lice,  soft 
scales  and  other  insects  for  honey-dew  and  to  some  extent  at  least,  their 
presence  is  favorable  to  these  pests  and  makes  their  control  more  difficult. 


THE  HYMENOPTERA  373 

Control. — Heavy  rains,  causing  a  flooding  of  the  nests  is  a  natural  means 
of  checking  the  ravages  of  these  insects,  many  being  killed,  particularly 
in  cold  weather.  Barriers  on  the  legs  of  tables,  beds,  etc.,  consisting  of 
tape,  soaked  in  a  saturated  solution  of  corrosive  sublimate  (Hg  C12), 
dried,  and  then  fastened  around  such  places  will  keep  the  ants  away  for 
several  months  at  least.  A  generous  supply  of  naphthaline  in  the  form 
of  moth  balls,  placed  in  a  dish  in  which  a  leg  of  a  piece  of  furniture  rests  is 
also  effective,  provided  each  leg  is  thus  treated.  Kerosene  instead  of  moth 
balls,  as  already  described,  is  generally  of  some  value  as  a  protection. 

Various  ant  poisons  have  been  tested,  and  a  syrup  of  granulated 
sugar,  water,  tartaric  acid,  sodium  arsenite  and  honey  has  been  found 
to  be  very  effective,  and  it  also  keeps  well.  Placed  in  a  tight  tin  with 
two  sides  dented  in  and  with  a  tin  cover,  the  ants  can  enter  and  feed 
while  the  syrup  remains  protected  from  the  weather.  A  gill  or  two  of 
syrup  and  a  fairly  large  piece  of  sponge  floating  in  it  will  complete  the 
trap  for  use.  Traps  should  be  placed  both  in  and  around  the  house,  of 
course  out  of  the  reach  of  children,  and  by  adding  a  bail  or  handle  can 
be  hung  on  walls,  the  branches  of  trees  and  in  similar  situations.  Eight 
or  ten  of  these  are  sufficient  for  an  ordinary  city  house  and  lot  and  will 
be  effective  at  least  for  6  or  8  weeks. 

House  Ants. — These  are  of  several  kinds  but  the  one  most  usually 
troublesome  is  the  Little  Red  Ant  (Monomorium  pharaonis  L.),  probably 
a  native  of  Europe  but  now  abundant  in  nearly  all  countries.  It  is  very 
small,  red  in  color,  and  makes  its  nests  in  walls,  floors,  sills  or  other 
timbers,  whence  it  explores  all  parts  of  the  houses,  paying  particular 
attention  to  those  places  where  food  is  found.  Oftentimes  regular  lines 
of  these  pests  may  be  found  marching  from  some  article  of  food  they 
have  discovered  to  their  nest,  and  another  line  beside  the  first,  on  their 
way  to  obtain  food.  In  such  cases  it  is  sometimes  easy  to  trace  their 
line  of  march  back  to  where  they  enter  some  timber  in  which  their  nest 
is  placed,  and  then  the  injection  into  the  holes  where  they  enter, 
of  carbon  disulfid  or  benzine  may  prove  sufficient  to  kill  the  queen 
or  queens  and  terminate  the  life  of  the  colony.  In  too  many  cases 
though,  it  is  impossible  to  locate,  or  perhaps  to  reach  the  nest.  Where 
this  is  true  it  has  been  found  that  small  pieces  of  sponge,  soaked  in  mo- 
lasses and  water,  and  a  little  arsenic,  placed  where  ants  are  will  generally 
attract  the  pests,  which  will  feed  upon  the  poisoned  syrup  and  be  killed. 
In  this  way  the  number  of  individuals  is  frequently  reduced  more  rapidly 
than  the  colony  increases  and  the  ants  gradually  become  less  abundant 
and  finally  disappear.  Simple  protection  of  food  or  other  materials  can 
usually  be  obtained  by  placing  around  such  articles  a  continuous,  liberal 
band  of  powdered  cloves. 

Where  ants  are  nesting  in  living  trees  they  usually  enter  where  some 
limb  has  been  lost,  and  their  entrance  holes  in  the  wood  can  be  found. 


374 


APPLIED  ENTOMOLOGY 


Pouring  carbon  disulfid  or  benzine  into  these  and  then  stopping  the 
holes  with  putty  or  mud  is  in  most  cases,  sufficient  to  kill  the  queen,  and 
in  consequence,  the  colony. 

Ants  in  lawns  or  elsewhere  may  make  mounds  (Fig.  388)  or  may 
simply  loosen  the  soil  and  more  or  less  injure  the  grass  at  such  places. 
To  destroy  such  nests  a  stick,  such  as  a  cane  or  a  broom  handle,  should  be 
driven  down  to  the  bottom  of  the  nest,  at  which  point  the  loosened  earth 
ends  and  driving  becomes  hard.  These  holes  should  be  about  a  foot 


FIG.  388. — Ant  hills.      (From  a  photograph  by  H.  B.  Peirson.) 

apart  and  enough  of  them  be  made  to  cover  the  entire  surface  of  the  nest 
at  this  distance.  Into  each  hole  a  tablespoonful  or  two  of  carbon  di- 
sulfid  is  now  poured  and  each  opening  closed  at  the  top,  which  is  suffi- 
ciently done  by  pressing  the  earth  together  at  each  hole  with  the  foot. 
The  carbon  disulfid  gas  penetrating  through  the  underground  galleries 
of  the  ants  will  kill  them,  including  the  queen,  and  the  colony  will 
disappear. 

This  treatment  should  be  applied  on  a  warm,  dry  day,  to  hasten  the 
change  of  the  liquid  to  the  gas  and  its  rapid  dissemination  through  all 
parts  of  the  nest. 


INDEX 


Abdomen,  14 

Abdominal  feet,  14,  232,  252,  272,  300 

Acrididae,  81-85 

Aculeata,  339 

Adalia  bipunctata,  133 

Aedes  aegypti,  309 

sollicitans,  307 
^Egeriidse,  243-246 
Agamic  reproduction,  154,  196 
Agglomerate  eyes,  9 
Air  tubes,  18 
Alabama  argillacea,  269 
Alaus  oculatus,  108 
Aleyrodes  vaporariorum,  207 
Aleyrodida,  187,  206-208 
Alfalfa  caterpillar,  295 

weevil,  143 

worm,  274 

Alsophila  pometaria,  253 
Amblychila  cylindriformis,  101 
Ambrosia  beetles,  146 
Ambush-bugs,  182 
American  roach,  78 
Ametabola,  25 

development  of,  26 
Anabrus  purpurascens,  87 
Anatis  15-punctata,  134 
Angoumois  Grain  Moth,  247 
Anisolabris  maritima,  95 
Annulata,  1 
Anopheles  crucians,  309 

quadrimaculatus,  307 
Anoplura,  164-167 

mouth  parts  of,  164 
Ant,  Argentine,  371 

-lions,  224-225 

little  brown,  204 

red,  373 
Ants,  186,  196,  197,  204,  367-374 

house,  373 

in  lawns,  374 
Antennae,  8 
Anthomyiidae,  327-330 
Anthonomus  grandis,  140 


Anthrax,  323 

Anthrenus  scrophulariae,  104 

Antique  tussock  moth,  262 

Anuraphis  roseus,  198 

Anus,  15 

Aorta,  19 

Apex,  14 

Aphididae,    133,    187,  194-206,  291,  344, 

368,  370 
Aphis  bakeri,  199 

-lions,  222 

maidi-radicis,  203 

pomi,  198 
Apis  mellifera,  362 
Apoidea,  360-367 
Apple  aphids,  198 

grain  aphis,  198 

leaf  hoppers,  192 

maggot,  319 

-tree  tent-caterpillar,  256 
Apterygota,  60,  62 

characters  of,  62 
Arachnida,  2 

characters  of,  4 
Arctiidae,  277-279 
Armored  scales,  208,  209-216 
Army  worm,  272 
Arsenate  of  lead,  46 

standard  formula,  47 

of  lime,  47 
Arsenic,  44 
Arthropod  characters,  1 

groups  of,  2 

distinctive  table  of,  5 
Arthropoda,  1 

Artificial  control  methods,  38 
Asilidae,  316 
Asparagus  beetle,  123 
Aspidiotus  perniciosus,  211 
Attagenus  piceus,  104 
Aulacaspis  rosae,  214 
Australian  roach,  78 
Automeris  io,  286 
Axillary  incision,  301 
Axillary  sinus,  301 
375 


376 


INDEX 


Bacillus  pestis,  334 
Back-swimmers,  184 
Bacterial  wilt,  118,  197 
Bag  worms,  250-252 
Bark  beetles,  146-149 
Basilarchia  archippus,  292 
Basilona  imperialis,  281 
Bean  weevils,  128-130 
Bedbug,  182 
Bee  bread,  365 

moth,  249 
Bees,  360-367; 

bumble,  361 

carpenter,  361 

honey,  362 

leaf-cutter,  361 

solitary,  360 
Beetles,  98-149 
Beet-root  louse,  205 
Belostomidse,  185 
Bembecidse,  354 
Bilateral  symmetry,  2 
Bird  lice,  161-163 
Birds,  1;  and  insects,  35,  36 
Biting  lice,  161-163 
Black-beetle,  78 

carpet  beetle,  104 

flies,  315 

lady  beetle,  135 

scale,  135,  216,  220 

swallow-tail  butterfly,  298 

witch,  269 

Blastophaga  grossorum,  349 
Blatella  germanica,  76 
Blatta  orientalis,  78 
Blattidae,  76-78 
Blissus  leucopterus,  174 
Blister  beetles,  135-136 
Blood,  20 

vessels,  19 
Blue-bottle  flies,  324 
Bombus,  361 
Bombycidse,  255 
Bombyx  mori,  255 
Book-lice,  159 
Borax,  50 

Bordeaux  mixture,  54 
Bot  flies,  318 
Brain,  21 

Breathing  organs,  17 
Broad  bean  weevil,  129 


Bromius  obscurus,  125 
Brown-tail  moth,  265,  296,  297 
Bruchidse,  128-130 
Bruchophagus  funebris,  349 
Bruchus  chinensis,  129 

obtectus,  129 

pisorum,  128 

quadrimaculatus,  129 

rufimanus,  129 
Bubonic  plague,  334 
Bud-worm  (of  corn),  120 
Buffalo  carpet  beetle,  104 

gnats,  315 

Tree-hopper,  190 
"Bug  vs.  bug,"  220 
Buhach,  53 
Bumblebees,  361 
Buprestidse,  105-107 
Burning  insects,  40 
Butterflies,  290-299 

(and  moths),  230-299 


Cabbage  butterfly,  imported,  293 

maggot,  327 
Caddice  flies,  226-229 
Caeca,  16 
California  devastating  grasshopper,  83 

grape-root  worm,  125 

oak  worm,  267 
Caliroa  cerasi,  341 
Callosamia  promethea,  283 
Calosoma  sycophanta,  100 
Camel  crickets,  86 
Camnula  pellucida,  84 
Camphor  thrips,  158 
Canker  worms,  253 
Cantharidin,  136 
Capsidae,  180 
Carabidae,  100 
Carbon  disulfid,  55 
Carnivorous  diving  beetles,  101 
Carolina  grasshopper,  84 
Carpenter  bees,  361 

moths,  234-236 

worm,  234 
Carrion  beetles,  103 
Case-making  clothes  moth,  236 
Caterpillar,  232 
Catocalas,  269 
Cecropia  moth,  283 
Cells,  13 


INDEX 


377 


Centipedes,  2 

characters  of,  3 
Cephalothorax,  3,  151 
Cephus  cinctus,  342 

pygmaeus,  342 
Cerambycids,  130-133 
Ceratocampidae,  280 
Cerceridae,  354 
Cerci,  14 

Ceresa  bubalus,  190 
Chalcid  flies,  347-351 
Changa,  90 

Characters  of  Arthropods,  1 
Chermidje,  187,  193 
Cherry  plant  lice,  205 
Chigoe,  336 

Chilocorus  bivulnerus,  134,  213 
Chilopoda,  2 

characters  of,  3 
China  wax,  209 
Chinch  bug,  174 

bug  fungus,  176 
Chinese  mantis,  79 
Chionaspis  furfura,  210 

pinifolise,  215 
Chitin,  2,  7 

Chloridea  obsoleta,  270 
Cholera,  321,  323 
Chordata,  1 
Chrysalis,  234 
Chrysidoidea,  353 
Chrysobothris  femorata,  106 
Chrysomelidae,  115-128 
Chrysomphalus  aurantii,  215 
Chrysomyia  macellaria,  324 
Chrysopidse,  222-223 
Cicada-killer,  355 
Cicadas,  187-190,  355 
Cicadidse,  187-190 
Cicindelidae,  101 
Cimex  lectularius,  182 
Cimicidae,  182 
Circulatory  organs,  19 
Cirphis  unipuncta,  272 
Citheronia  regalis,  280 
Citrus  mealy  bug,  218 

thrips,  157 

white  fly,  207 
Classification,  59-61 
Clean  culture,  39 
Clear-winged  grasshopper,  84 

moths,  243-247 
Click-beetles,  107-110 


Closed  cells,  13 
Clothes  moths,  236-238 
Clover  aphis,  199 

-flower  midge,  311 

root-borer,  147 

-seed  chalcid,  349 
Cnidocampa  flavescens,  250,  353 
Coccidse,  187,  208-220 
Coccinella  novemnotata,  134 
Coccinellidae,  133-135 
Coccotorus  scutellaris,  139 
Cochineal,  209 
Cocoon,  29 

in  Lepidoptera,  233 
Codling  moth,  238 
Coelenterata,  1 
Coleomegilla  fuscilabris,  134 
Coleoptera,  98-149 
Coleoptera  vera,  99-136 
Collembola,  62,  63-64 
Colon,  16 

Colorado  potato  beetle,  115 
Comb,  364 

Combinations  of  sprays,  54 
Commissures,  21 
Common  bean  weevil,  129 
Compound  eyes,  8 
Conotrachelus  nenuphar,  137 
Contact  insecticides,  43,  49-53 
Contarinia  tritici,  314 
Control  by  natural  methods,  35 
Coreidse,  172-173 
Corixidae,  184 
Corn  borer,  European,  249 

ear  worm,  270 
Cornicles,  195 
Corn-root  aphis,  203,  370 

worms,  120-122 
Corrodentia,  159-161 
Corydalis  cornuta,  221 
Cossidse,  234-236 
Costa,  14 
Cotton  boll  weevil,  140 

stainer,  174 

worm,  269 

Cottony  cushion  scale,  135,  219, 
220 

maple  scale,  217 
Cowpea  weevil,  129 
Coxa,  12 
Crab  louse,  166 
Crane  flies,  304 
Crickets,  88-90 


378 


INDEX 


Crioceris  asparagi,  123 

duodecimpunctata,  124 

Crop,  16 

rotation,  39 

Croton  bug,  76 

Crude  petroleum,  50 

Crustacea,  2 

characters  of,  3 

Cryptolsemus  montrouzieri,  135 

Cuckoo  wasps,  353 

Cucurbit  mosaic  disease,  118 

Culex  pipiens,  306 

Culicidse,  305-311 

Curly-leaf  disease,  193 

Currant  worm,  340 

Cursorial  Orthoptera,  75-81 

Cutworms,  275 

Cydnidec,  172 

Cylas  formicarius,  145 

Cyriipoidea,  346 


D 


Dagger  moths,  270 

Damsel-flies,  68-69 

Danaidae,  291 

Danaus  archippus,  291 

Darkling  beetles,  135 

Dasyneura  leguminicola,  311 

Datana,  267 

Death  watch,  160 

Dengue,  310 

Dermaptera,  95-97 

Dermestes  lardarius,  103 

Dermestidse,  103-105 

Diabrotica  duodecimpunctata,  120 

longicornis,  121 

soror,  122 

trivittata,  119 

vergifera,  122 

vittata,  118 
Dialeurodes  citri,  207 
Diapheromera  femorata,  81 
Differential  grasshopper,  83 
Digestion,  16 
Digestive  organs,  15 
formation,  15 
Digger  wasps,  354—356 
Dimorphism,  seasonal,  291 
Dioptidse,  267 
Diplopoda,  2 

characters  of,  3 
Diptera,  301-332 


Diseases    carried   by   insects,    166,    167, 

183,  309,  321-323,  325,  334 
Diseases  of  insects,  178 
Dispersion  of  insects,  296 
Dissosteira  Carolina,  84 
Dobson,  221 
Doodle-bug,  224 
Dog-day  harvest-flies,  189 
Doryphora  clivicollis,  117 
Dragon-flies,  68-71 
Drill-worm,  120 
Drones,  362,  363 
Dry  sulfur  compounds,  52 
Dusting  poisons,  43 
Dynastes  tityrus,  114 
Dysdercus  suturellus,  174 
Dysentery,  321 
Dytiscidae,  101 
Dzierzon  theory,  365,  369 


E 


Earwigs,  95-97 

Eccoptogaster  nigulosus,  147 

Ecdysis,  27 

Echidnophaga  gallinacea,  336 

Echinodermata,  1 

Eggs,  25 

Ejaculatory  duct,  24 

Elateridse,  107-110 

Electric-light  bugs,  185 

Elm  leaf  beetle,  126 

Elytra,  98 

Embiidina,  74 

Emergence,  30 

Empoa  rosae,  193 

Empoasca  mali,  192 

Empodium,  12,  303 

Engraver  beetles,  136,  146-149 

Ensign  flies,  343 

Ephemerida,  65-67 

Ephestia  kuhniella,  249 

Epipharynx,  9 

Erebus  odorata,  269 

Eriosoma  lanigera,  199 

Estigmene  acraea,  277 

Eucosmida?,  238-243 

Eulecanium  nigrofasciatum,  217 

tulipiferse,  216 
Eumenidse,  357 
Euproctis  chrysorrhoea,  265 
European  corn  borer,  249 

earwig,  95 


INDEX 


379 


Eurymus  eurytheme,  295 

philodice,  295 
Evaniidae,  343 
Excretory  organs,  21 
External  skeleton,  2 
Eyed  elater,  108 
Eyes,  8 

agglomerate,  9 


Fall  army  worm,  274 
canker  worm,  253 
webworm,  278 

False  budworm  of  tobacco,  270 
Farm  practices,  38 
Femur,  12 

Fever:  Relapsing,  166 
Trench,  166 
Typhus,  166 
Fidia  viticida,  125 
Field  crickets,  88 
Fifteen-spotted  Lady  beetle,  134 
Fig  fertilization  by  Blastophaga,  349 
Filariasis,  310 
Fire  blight,  181,  197 

-flies,  100 
Fishes,  1 
Fish-flies,  222 
Flat-headed  apple-tree  borer,  106 

borers,  105-107 
Flax-seed  stage,  312 
Flea-beetles,  122 
Fleas,  333-337 
Flesh  flies,  326 
Flies,  301-332 
.Fluted  scale,  135,  219,  220 
Forceps  in  Thysanura,  63 

in  Dermaptera,  95 
Fore-intestine,  15 
Forest  tent-caterpillar,  259 
Forficula  auricularia,  95 
Formicoidea,  367-374 
Four-spotted  bean  weevil,  129 
Frankliniella  tritici,  154 
Frenal  fold,  338 
hooks,  338 
Frenulum,  232 
Froghoppers,  191 
Fruit  flies,  319-321 

tree  bark-beetle,  147 
Fumigation,  18,  55 


G 

Gad  flies,  314 
Galerucella  luteola,  126 
Galleria  melonella,  249 
Gall  insects,  346 
midges,  311 

Galls:  Aphid,  196,  202,205 
Chalcidoid,  347 
Cynipoid,  346 
Itonidid,  311 
Trypetid,  319 
Gasoline  torches,  40 
Gastric  caeca,  16 
Gastrophilus,  319 
Gelechiidae,  247 
Geometridae,  252-255 
German  honey  bee,  362 

roach,  76 
Gerridae,  184 
Giant  silkworms,  283-287 

water-bugs,  185 
Glossina,  325 
Glow-worms,  100 
Goat  moth,  234 
Golden-eyes,  222 
Grape  Phylloxera,  201 

-root  worm,  125 
Grass-feeding  Froghopper,  191 
Grasshoppers,  81-85 
thrips,  158 
worm,  274 

Green  apple  aphis,  198 
-bottle  flies,  324 
fruit  worms,  270 
grasshoppers,  85-87 
-heads,  315 
Japanese  beetle,  114 
Greenhouse  thrips,  155,  158 

white  fly,  207 
Ground  beetles,  100 
Groups  of  Arthropods,  2 

distinctive  characters  of,  5 
Grouse  locusts,  85 
Gryllidae,  88-90 
Gryllus  luctuosus,  88 
Guests  in  galls,  347 
Gypsy  moth,  100,  262,  296 
Gyrinidse,  101 

H 

Halisidota  caryse,  277 
Halteres,  14,  301 


380 


INDEX 


Hamuli,  338 
Hand  picking,  40 
Harlequin  bug,  171 
Harmolita  grande,  348 

tritici,  348 

Harpalus  caliginosus,  100,  117 
Harvest  flies,  Dog-day,  189 
Hawk  moths,  287-290 
Head,  7 

Healthy  crops,  39 
Hearing :  in  crickets,  88 

in  grasshoppers,  85 

in  green  grasshoppers,  87 
Heart,  19 
Heat,  41 

Hedgehog  caterpillar,  277 
Heliothrips  haemorrhoidalis,  155 
Hellebore,  48 
Hellgrammite,  221 
Hemerocampa  leucostigma,  260 
Hemielytra,  168 
Hemimetabola,  26 
Hemiptera,  168-185 
Hemispherical  scale,  218 
Hesperiidae,  290 
Hessian  fly,  312 
Heterocera,  234 
Heterometabola,  26 
Hexapoda,  2 

characters  of,  5 

as  a  class,  59 
"  Hickory  horned  devil,"  280 

tiger  moth,  277 
Hind-intestine,  15 
Hippodamia  convergens,  134 
Hive  bee,  362 
Holometabola,  26 

development  of,  27 
Homoptera,  186-220 
Honey,  364 

ants,  371 

bees,  362 

-dew,  186,  194,  195,  217,  368,  370 

sac,  364 
Hornets,  360 
Horn-tails,  343,  344 
Horse  bot  flies,  319 

flies,  314 
House  ants,  373 

fly,  297,  321 

mosquito,  306 
Human  body  louse,  165 
Humming  bird  moths,  287-290 


Hydrocyanic  acid  gas,  57 
HydrophilidaB,  102 
Hylemyia  antiqua,  329 

brassicse,  327 
Hymenoptera,  338-374 
Hyperparasites,  344 
Hyphantria  cunea,  278 
Hypoderma  bovis,  318 

lineatum,  318 
Hypodermis,  7 
Hypognathous,  8 
Hypopharynx,  10 

I 

Icerya  purchasi,  135,  219 

Ichneumon  flies,  343-346 

Ichneumonoidea,  343-346 

Ileum,  16 

Imaginal  buds,  28 

Imago,  28 

Imperial  moth,  281 

Imported  cabbage  butterfly,  293,  296 

Inch  worms,  252-255 

Inquilines,  347,  361,  362 

Insecticides,  43 

classes  of,  43 
Insect  orders;  their  relations,  60 

powder,  53 
Insects,  2 

characters  of,  5 

external  structure  of,  6 

internal  structure  of,  15 
Instar,  27 

Introduced  insects,  35,  296 
lo  moth,  286 
Ipida?,  146-149 
Iridomyrmex  humilis,  371 
Isabella  tiger  moth,  277 
Isia  isabella,  277 
Isoptera,  91-93 
Italian  honey  bee,  363 
Itonididse,  311-314 


Japanese  beetle,  Green,  114 
Japanese  silkworm  moth,  284 
Jelly-fish,  1 
Jerusalem  crickets,  87 
Jigger  flea,  336 
Jugum,  232 

Jumping  plant  lice,  187,  193 
June  bugs,  110 


INDEX 


381 


K 

Kala-azar,  183 
Katydids,  85-87 
Kellogg,  349 
Kerosene  emulsion,  49 


Labia  minor,  95 

Labial  palpus,  10 

Labium,  10 

Labrum,  9 

Lace  bugs,  179 

Lace  wings,  222 

Lady  beetles,  bugs  or  birds,  133-135 

Lamellicorn  beetles,  110-115 

Lampyridse,  100 

Laphygma  frugiperda,  274 

Larder  beetle,  103 

Lasiocampidse,  256-260 

Lasius  niger  americanus,  204 

Laspeyresia  pomonella,  238 

Leaf  beetles,  115-128 

-cutter  bees,  361 

hoppers,  187,  190,  191 

insects,  81 
Legs,  10,  12 

abdominal,  14 
Lenticels,  216 
Leopard  Moth,  234 
Lepidoptera,  230-299 
Lepidosaphes  beckii,  215 

ulmi,  209 

Lepisma  saccharina,  63 
Leprosy,  183 

Leptinotarsa  decimlineata,  115 
Lesser  migratory  grasshopper,  84 
Lice:  biting,  161-163 

on  animals,  166 

sucking,  164-167 
Limacodidae,  250 
Lime-sulfur  wash,  51 

self-boiled,  52 
Little  brown  ant,  204 

earwig,  95 
Lochhead,  269 
Longicorn  beetles,  130-133 
Long-tailed  mealy  bug,  219 

Pelecinus,  351 

Thalessa,  345 
Losses  by  insects,  32 

crop,  32 

difficulties  of  estimation,  33 


Losses,  health,  32 

figures  on,  34 

increase  in,  34 
"Lubber"  grasshoppers,  84 
Luminous  organs,  100,  109 
Luna  moth,  286 
Lunula,  301 
Lycaenidae,  290 
Lygaeidae,  174 
Lygus  pratensis,  181 
Lymantriidae,  260-266 

M 

Macrodactylus  subspinosus,  113 
Macrolepidoptera,  234 
Maggots,  303 
Malacosoma  americana,  256 

disstria,  259 

Malaria,  309  . 

Malarial  mosquitoes,  307 
Mallophaga,  161-16& 
Malpighian  tubes,  21 
Mammals,  1 
Mandibles,  9 
Mantidae,  78 
Mantis,  common,  79 

Chinese,  79 

European,  79 

religiosa,  79 
Mantispa,  224 
Mantispidae,  224 
Marlatt,  142 
Mask,  71 

Masked  bedbug  hunter,  182 
Mason  wasps,  358 
Maxillae,  9 
Maxillary  palpus,  10 
May  beetles,  110 

-flies,  65-67 
Meadow  plant-bug,  180 
Mealy  bugs,  208,  218-220 

destroyer,  135 
Measuring  worms,  252-255 
Mecoptera,  300 
Median  segment,  12,  338 
Mediterranean  flour  moth,  249 
Melanoplus  atlanis,  84 

bivittatus,  84 

devastator,  83 

differentialis,  83 

femur-rubrum,  83 

spretus,  82 
Melittia  satyriniformis,  245 


382 


INDEX 


Meloidse,  135-136 

Melophagus  ovinus,  330 

Metamorphosis,  25 

Microlepidoptera,  234 

Mid-intestine,  15 

Millipedes,  2 

characters  of,  3 

Miridae,  180 

Miris  dolobratus,  180 

Miscible  oils,  50 

Miscellaneous  control  methods,  41 

Mites,  2 

Mole  crickets,  88 

Mollusca,  1 

Molting,  26    . 

number  of  molts,  27 

Monarch,  291,  297 

Monomorium  pharaonis,  373 

Mosquitoes,  305-311 

Moths,  234-290 

(and  butterflies),  230-299 

Mouth  cavity,  15 
parts,  9 

in  Anoplura,  164 
in  Apterygota,  62 
in  Diptera,  302 
in  Hemiptera,  168 
in  Homoptera,  186 
in  Hymenoptera,  339 
in  Lepidoptera,  230 
in  Siphonaptera,  333 
in  Thysanoptera,  153 

Murgantia  histrionica,  171 

Murky  ground  beetle,  100,  117 

Musca  domestica,  321 

Muscida?,  321-326 

Mutillidae,  356 

Myiasis,  318 

Myrmeleonidae,  224-225 


Nine-spotted  lady  beetle,  134 
Noctuidse,  268-277 
Nodus,  68 

Northern  tobacco  worm,  288 
Notodontidae,  266 
Notolophus  antiqua,  262 
NotonectidaB,  184 
Notum,  7 

Novius  cardinalis,  135,  219 
Number  of  segments,  6 
Nymph,  27,  31 
Nymphalidae,  292 


0 


Oak  worm,  California,  267 
Oat  blight,  197 
Ocelli,  8 
Odonata,  68-71 
(Esophagus,  16 
(Estridae  318 
(Estrus  ovis,  319 
Onion  maggot,  329 

thrips,  155 
Orcus  chalybeus,  135 
Orders:  their  relation,  60 
Oriental  moth,  250,  353 

roach,  78 
Orneodidae,  248 
Orthoptera,  75-90 
Ovary,  23 

Overflow  worm,  274 
Oviduct,  23 
Oviparous  insects,  25 
Ovipositor,  14,  338 
Owlet  moths,  268-277 
Ox  warbles,  318 
Oyster-shell  scale,  209,  220 


N 


Nagana,  326 

Natural  control  methods,  35 
Necrophorus,  103 
Negro-bugs,  172 
Nepidae,  185 
Nerve  ganglia,  21 
Nervous  system,  21 
Neuroptera,  221-225 
Neuters,  22 
Nicotine,  50,  56 
sulfate,  51 


Pacific  peach  borer,  243 

Paleacrita  vernata  254 

Papilionidae,  298 

Papilio  polyxenes,  298 

Paradichlorobenzine,  245 

Parasites  36,  344,  347 

Parasitism,  352 

Paratenodera  sinensis,  79 

Paris  green,  45 

Parthenogenesis:  in  aphids,  196 
in  gall  insects,  346 
in  Thysanoptera,  154 


INDEX 


383 


Patagiae,  231 

Pea  and  bean  weevils,  128-130 

louse,  205 

weevil,  128 
Peach  Borer,  243 

"stop-back,"  181 
Pear  Psylla,  193 

slug,  341 

thrips,  150 
Pedicel,  338 

Pediculus  humanus,  165 
Pelecinus  polyturator,  351 
Pentatomidae,  171 
Pentilia  misella,  134 
Periodical  cicada,  187 
Periplaneta  americana,  78 
Periplaneta  australasiae,  78 
Petiole,  338,  354,  367 
Phasmidse,  80 
Philaenus  lineatus,  191 
Philosamia  cynthia,  284 
Phlegethontius  quinquemaculata,  288 

sexta,  288 

Phryganidia  californica,  267 
Phthirus  pubis,  166 
Phyllophaga,  110 
Phylloxera  vitifolise,  201 
Phymatidse,  182 
Phytonomus  posticus,  143 
Phytophaga  destructor,  312 
Picking  by  hand,  40 
Pieridae,  293-296 
Pigeon  Tremex,  343 
Pine-leaf  scale,  215 

weevil,  white,  142 
Pissodes  strobi,  142 
Pitiful  lady  beetle,  134 
Plague,  183 
Plant  lice,  133,  187,  194-206,  291,  344*, 

368,  370 

Planting,  time  of,  40 
Plecoptera,  72-73 
Pleuron,  7 
Plowing,  39 
Plum  curculio,  137 

gouger,  139 
Porthetria  dispar,  262 
Poison  baits,  47 
Polistes,  358 
Pollen  baskets,  363 
Polyphemus  moth,  283 
Pontia  rapse,  293 
Popillia  japonica,  114 


Potato  plant  louse,  205 

-stalk  weevil,  145 
Praying  mantids,  78 
Primary  parasites,  344 
Prionoxystus  robinise,  234 
Proctotrypoidea,  351 
Prognathous, '8 
Promethea  moth,  283 
Prominents,    266 
Propodeum,  12,  338 
Propolis,  364 

Prospaltella  perniciosi,  220 
Protective  imitation,  292 
Protozoa,  1 
Proventriculus,  16 
Pseudococcus  citri,  218 

longispinus,  219 
Pseudoscorpions,  2 
Psithyrus,  362 
Psocids,  159-161 
Psyllia  pyricola,  193 
PsychidsB,  250-252 
Pteromalus  puparum,  350 
Pteronidea  ribesii,  340 
Pterophoridse,  248 
Pterygota,  60,  65 
Ptilinum,  301 

Pulchriphyllium  scythe,  81 
Pulvillus,  12,  303 
Pulvinaria  vitis,  217 
Pupa,  29 

libera,  99,  339 

obtecta,  30,  99 
Puparium,  29,  303 
Pupipara,  330-332 
Purple  scale,  215 
Pyralidae,  248-250 
Pyrausta  nubilalis,  249 
Pyrethrum,  53 
Pyrophorus  spp.  109 
Pyrrhocoridae,  173 


Railroad  worm,  319 

Raphidiidae,  224 

Rear-horses,  78-80 

Rectal  gills,  71 

Rectum,  16 

Red-humped  apple-tree  caterpillar,  267 

-legged  grasshopper,  83 

scale,  215 
Reduviidse,  182 


384 


INDEX 


Relapsing  fever,  166,  183 
Relations  of  insect  orders,  60 
Repellents,  40 
Reproductive  organs,  22 
Reptiles,  1 
Respiration,  17 
Reticulitermes  flavipes,  93 
Rhagoletis  pomonella,  319 
Rhinoceros  beetles,  114 
Rhizobius  ventralis,  135 
Rhopalocera,  234,  290-299 
Rhopalosiphum  prunifolise,  198 
Rhynchophora,  99,  136-149 
Roaches,  76-78 
Robber  flies,  316 
Rocky  mountain  locust,  82 
Rose  chafer,  113 

leafhopper,  193 

scale,  214 
Rostrum,  168 
Round-headed  apple-tree  borer,  131 

borers,  130-133 
Rove-beetles,  102 
Royal  jelly,  366 

moths,  280 
Rusty  tussock  moth,  262 


Saltatorial  Orthoptera,  81-90 
Salt  marsh  caterpillar,  277 

mosquito,  307 
Samia  cecropia,  283 
San  Jose  scale,  211,  220 
Saperda  Candida,  131 
Sarcophagidse,  326 
Saturniidae,  283-287 
Satyridae,  293 
Saw-flies,  340-343 
Scale  insects,  187,  208-220 
Scapteriscus  vicinus,  90 
Scarabseida),  110-115 
Scarabseus,  110 
Schizura  concinna,  267 
Scirtothrips  citri,  157 
Sclerites,  7 
Scolytida3,  146-149 
Scorpion  flies,  300 
Scorpions,  2 
Screw-worm  fly,  324 
Scurfy  scale,  210 
Scutellista  cyanea,  220 
Scutellum,  168 


Sea  urchin,  1 
Seasonal  dimorphism,  291 
Secondary  parasites,  344 
Seminal  receptacle  23 
Sense  organs,  22 
Serphoidea,  351 
SesiidaB,  243 

Seventeen-year  locust,  187 
Sexes  of  insects,  22 
Shad-flies,  65 
Sheep  bot  fly,  319 

tick,  330 
Shell  gland,  23 
Shellac,  209 
Shot-hole  borer,  147 
Sialida?,  221 
Silk,  29,  255 

glands,  227,  233 

worm,  255 

Silpha  americana,  103 
Silphidae,  103 
Silver  fish,  63 
Simulidse,  315 
Siphonaptera,  333-337 
Sitotroga  cerealella,  247 
Skeleton,  7 
Skip-jacks,  107-110 
Skippers,  290 
Slave-making  ants,  370 
Sleeping  sickness,  325 
Slug  caterpillars,  250 
Snails,  1 

Snapping-beetles,  107-110 
Snout  beetles,  136-149 
Snow  fleas,  64 
Soap,  50 

Social  wasps,  356-360 
Sodium  fluorid,  48 
Soft  scales,  208,  216-218 
Solitary  bees,  360 
Soothsayers,  78 
Sooty  mould,  207 
Sounds  produced  by  crickets,  88 

by  grasshoppers,  85 

by  green  grasshoppers,  87 
Southern  corn-root  worm,  120 
Southern  tobacco  worm,  288 
Spanish  flies,  136 
Span  worms,  252-255 
Spermaries,  24 
Sphecius  speciosus,  355 
Sphecoidea,  354-356 
Sphingidse,  287-290 


INDEX 


385 


Spiders,  2 
Spinneret,  231,  233 
Spiracles,  18 
Spittle  insects,  191 
Sporotrichum  globuliferum,  176 
Spotted  lady  beetle,  134 
Sprays,  44 

combinations  of,  54 
Spring  canker  worm,  254 
" Spring"  of  Collembola,  63 
Springtails,  63 
Squash  bug,  172 
Squash- vine  borer,  245 
Stagomantis  Carolina,  79 
Stalk  borers,  270 
Staphylinidse,  102 
Starfish,  1 

Steel-blue  lady  beetle,  135 
Stegomyia  fasciata,  309 
Stem-mothers,  196 
Sternum,  7 
Sticktight  flea,  336 
Sting,  14,  339 
Stinging  ants,  356 
Stink  bugs,  171 
Stomach,  16 

poisons,  43 

their  action,  17 
Stone-flies,  72 

"Stop-back"  of  peaches,  181 
Strawberry  thrips,  154 
Strepsiptera,  150-152 
Striped  cucumber  beetle,  118 
Stylops,  150-152 
Subcesophageal  ganglion,  22 
Sucking  lice,  164-167 
Sulfur,  52,  56 

compounds,  52 
Sutures,  7 

Swallow-tail  butterflies,  298 
Swarming;  of  ants,  369 

of  honey  bees,  365 

of  white  ants,  92 
Sweet  potato  weevil,  145 
Synanthedon  exitiosa,  243 
Synanthedon  opalescens,  243 
Syrphidae,  316 
Syrphus  flies,  316 


Tabanidae,    314 
Table  of  classification, 

25 


Tachina  flies,  273,  326 

Tachinidae,  326 

Taenidia,  334 

Taeniothrips  inconsequens,  156 

Tapestry  moth,  237 

Tarantula-killer,  357 

Tarnished  plant-bug,  181 

Tarsus,  12 

Tegulse,  231,  338 

Telea  polyphemus,  283 

Tenebrio  molitor,  135 

Tenebrionidse,  135 

Tent-caterpillars,  256-260 

Tenthredinoidea,  340-343 

Terebrantia,  339 

Termites,  91-93 

Terrapin  scale,  217 

Testes,  24 

Tettigoniidae,  85-87 

Thalessa,  long-tailed,  345 

Thorax,  10 

Thread-waisted  wasps,  354 

Three-spotted  Doryphora,  117 

Thrips,  153-158 

Thrips  tabaci,  155 

Thyridopteryx  ephemerseformis,  252 

Thysanoptera,  153-158 

Thysanura,  62 

Tibia,  12 

Tibicen  linnei,  189 

Tibicina  septendecim,  187 

Ticks,  2 

Tiger  beetles,  101 

moths,  277-279 
Time  of  planting,  40 
Tinea  pellionella,  236 
Tineidae,  236-238 
Tineola  biselliella,  236 
Tingididse,  179 
Tipulidae,  304 
Tobacco  worms,  288 
Tomato  fruitworm,  270 
Tortoise  beetles,  128 
Trachea,  18 
Tracheal  gills,  19,  71 
Trap  crops,  40 

lanterns,  40 
Tree  crickets,  90 

hoppers,  187,  190 
Tremex  columba,  343 
Trench  fever,  166 
Trichobaris  trinotata,  145 
Trichophaga  tapetzella,  237 


386 


INDEX 


Trichoptera,  226-229 
Tropaea  luna,  286 
True  bugs,  170 
Trypanosoma  gambiense,  325 
Trypetidae,  319-321 
Tsetse  flies,  325 
Tussock  moths,  260-266 
Twelve-spotted  asparagus  beetle,  124 

cucumber  beetle,  120 
Twice-stabbed  lady  beetle,  134,  213 
Twisted-wing  parasites,  150-152 
Two-spotted  lady  beetle,  133 

-striped  grasshopper,  84 
Tuberculosis,  323 
Tulip  tree  scale,  216 
Tunga  penetrans,  336 
Typhoid  fever,  321,  323 
Typhus  fever,  166 


U 


Underwings,  269 


Vagina,  23 

Value  of  honey  and  wax,  367 

Vas  deferens,  24 

Vedalia,  135,  219,  220 

Velvet  ants,  356 

Veratrum,  48 

Vespidse,  358 

Vespoidea,  356-360 

Vespula,  359 

Viceroy,  292 

Viviparous  insects,  25,  196,  212 


W 


Walking-sticks,  80-81 

Wasps,  progressive  development  in,  360 

Water-boatmen,  184 

"Water  bugs,"  76 

-scavenger  beetles,  102 

-scorpions,  185 


Water  skaters,  184 

Wax,  364 

Weather  conditions  and  insects,  36 

Webbing  clothes  moth,  236 

Webster,  314 

Western  corn-root  worm,  121 

cricket,  87 

grass-stem  borer,  342 

striped  cucumber  beetle,  119 

twelve-spotted  cucumber  beetle,  122 
Whale-oil  soap,  50 
Wheat  joint-worm,  348 

midge,  314 

-stem  borer,  342 

straw-worm,  348 

thrips,  154 
Wheeler,  370 
Whirligig  beetles,  101 
White  ants,  91-93 

flies,  187,  206-208 

grubs,  110-113 

marked  tussock  moth,  260 

pine  weevil,  142 
Wingless  grasshoppers,  86 
Wings,  12-14 

veins,  13 
Wireworms,  108 
Woolly  apple  aphis,  199 

bears,  277 


X 


Xylocopa,  361 


Yaws,  323 

Yellow-jackets,  359 
fever,  309 
fever  mosquito,  309 
meal-worm,  135 


Zoraptera,  94 


